B细胞活化因子在多发性骨髓瘤发病中的作用

多发性骨髓瘤(MM)是一种浆细胞恶性增殖性疾病.MM细胞的恶性增殖严重依赖其骨髓微环境.B细胞活化因子(BAFF)作为骨髓微环境的重要组分,在MM的发病过程中,发挥重要作用.MM细胞表达多种B细胞活化因子受体(BAFF-R).BAFF与BAFF-R结合后,激活MM发病过程中重要的信号通路——核因子-κB信号通路.与健康个体相比,MM患者BAFF的水平显著升高.因此,关于BAFF的相关研究,对于MM的治疗意义重大.笔者拟就BAFF在MM发病过程中发挥的促肿瘤作用进行综述.     

MAPK/FOXA2介导香烟烟雾提取物对支气管上皮细胞分化的影响

目的:探讨吸烟对支气管上皮细胞分化的影响及丝裂原活化蛋白激酶(MAPK)/叉头框转录因子A2(FOXA2)信号通路在此过程中发挥的作用。方法:培养BEAS-2B细胞,分为空白对照组、香烟烟雾提取物(CSE)处理组、CSE+ERK抑制剂U0126处理组、CSE+JNK抑制剂SP600125处理组、CSE+p38抑制剂SB203580处理组。ELISA测定各组磷酸化的ERK1/2、JNK、p38蛋白的水平;实时荧光定量PCR检测FOXA2、E-cadherin、CD44、ZO-1的mRNA水平;用Western印迹检测FOXA2、E-cadherin、CD44、ZO-1的蛋白水平。结果:与空白对照组相比,用CSE的细胞中磷酸化的ERK1/2、JNK、p38蛋白水平明显升高(P0.05),而FOXA2、E-cadherin、CD44、ZO-1的mRNA及蛋白表达水平均明显降低(P0.05);CSE处理同时采用ERK、JNK或p38抑制剂处理显著改善上述基因及蛋白表达的变化(P0.05)。结论:吸烟可影响支气管上皮细胞分化,而MAPK/FOXA2信号通路在此过程中发挥重要调节作用。     

BAFF及其特异性受体BAFF—R对多发性骨髓瘤细胞增殖及凋亡的影响研究

目的探讨B淋巴细胞刺激因子（BAFF）及其特异性受体BAFF—R对多发性骨髓瘤（MM）细胞增殖及凋亡的影响。方法采用流式细胞术（FCM）、RT—PCR、WesternBlot、荧光免疫细胞化学技术检测BAFF及其受体BAFF—R的表达与定位;wsT细胞增殖实验及TUNEL法检测BAFF及其受体BAFF—R对MM肿瘤细胞生长、存活与凋亡的影响。结果①MM细胞能够表达BAFF及其特异性受体BAFF—R;②BAFF及其受体BAFF—R定位表达于KM3细胞的浆膜上;③BAFF及其受体BAFF—R促进MM细胞的增殖、存活,抗细胞凋亡。结论BAFF及其受体BAFF—R对于骨髓瘤发生、发展可能起着重要的作用。     

过表达VCAM-1对小鼠间充质干细胞成脂分化的影响与作用机制

目的:探讨基因修饰过表达VCAM-1对小鼠间充质干细胞(MSC)成脂分化能力的影响与作用机制。方法:将稳定过表达VCAM-1的MSC细胞(MIGR1-VCAM-1)和转入空载体的MSC细胞(MIGR1)分别向脂肪细胞诱导分化,以原位油红O染色和real-time PCR检测成脂分化能力与相关关键转录因子C/EBPα和PPARγ的表达;Western blot检测相关信号通路P38、ERK和JNK通路的活化。利用信号通路抑制剂处理MSC,观察其成脂分化能力的变化。结果:无论是自分化组还是诱导分化组,过表达VCAM-1的MIGR1-VCAM-1/MSC与对照组MIGR1/MSC相比,脂滴变大,脂肪细胞数量显著增加(P0.01);同时在mRNA水平调控成脂分化的关键转录因子C/EBPα和PPARγ表达显著上调;Western blot检测相关信号通路,结果表明JNK通路在VCAM-1调控成脂分化中明显下调,P38及ERK通路则显著上调;加入通路抑制剂后,JNK通路抑制可显著上调MIGR1-VCAM-1/MSC成脂分化能力,脂肪数量明显增加(P0.01),且相关转录因子C/EBPα和PPARγ的mRNA表达也显著上升;而抑制P38及ERK通路则使MIGR1-VCAM-1/MSC的C/EBPα和PPARγ的mRNA表达水平下调,脂滴及脂肪细胞数则更小、更少。结论:过表达VCAM-1可促进小鼠MSC成脂分化,VCAM-1可能通过抑制JNK信号通路,活化P38及ERK通路促进小鼠MSC成脂分化能力。     

miR-188-5p通过靶向调控丝裂原活化蛋白激酶信号通路对大鼠移植肾慢性排斥反应的作用

目的探讨miR-188-5p通过靶向调控丝裂原活化蛋白激酶(mitogen activated protein kinase, MAPK)信号通路对大鼠移植肾慢性排斥反应的作用。方法 SPF级F344大鼠20只和Lewis大鼠40只,其中以Lewis大鼠供体10只、受体10只进行肾移植为对照组;以F344大鼠20只为供体,Lewis大鼠20只为受体行肾移植建立大鼠慢性排斥反应模型,并分为模型组和过表达组。3组均于术后连续注射环孢素A 1.5 mg/kg 10 d。过表达组术后当天同时注射miR-188-5p高表达慢病毒颗粒0.1 mL,对照组与模型组分别注射等量生理盐水。术后12周观察3组大鼠存活情况,比较3组大鼠肾功能指标;观察3组大鼠移植肾组织病理变化情况,采用慢性移植肾损伤指数评分系统评价移植肾损伤情况;采用反转录PCR法检测移植肾组织miR-188-5p、p38MAPK、细胞外调节蛋白激酶1/2(extracellular regulated protein kinase 1/2, ERK1/2)、c-Jun氨基末端激酶(c-Jun N-terminal kinase, JNK)mRNA相对表达量,采用Western blot法检测p38MAPK、ERK1/2、JNK蛋白及其磷酸化蛋白相对表达量,并比较p-p38MAPK/p38MAPK、(p-ERK1/2)/(ERK1/2)、p-JNK/JNK。结果术后12周3组大鼠均存活。模型组和过表达组血清肌酐水平、24 h尿蛋白定量、慢性移植肾损伤指数评分高于对照组(P0.05),模型组高于过表达组(P0.05)。移植肾组织病理学观察,对照组存在交界性改变,仅少量炎症细胞浸润;模型组慢性排斥反应病理改变明显,过表达组较轻。过表达组移植肾组织miR-188-5p相对表达量(1.90±0.22)高于模型组(0.62±0.18)和对照组(1.02±0.25)(P0.05),对照组高于模型组(P0.05);模型组p38MAPK、ERK1/2、JNK mRNA相对表达量,p-p38MAPK、p38MAPK、p-ERK1/2、ERK1/2、p-JNK蛋白相对表达量及p-p38MAPK/p38MAPK、(p-ERK1/2)/(ERK1/2)、p-JNK/JNK高于过表达组和对照组(P0.05),过表达组高于对照组(P0.05)。结论 miR-188-5p可有效抑制大鼠移植肾慢性排斥反应,其机制可能与靶向调控MAPK信号通路中相关基因的表达及蛋白磷酸化过程有关。     

硼替佐米联合阿糖胞苷协同诱导U937细胞凋亡机制的深入研究

本研究旨在探讨蛋白酶体抑制剂硼替佐米联合低浓度阿糖胞苷协同诱导U937细胞凋亡的机制。通过细胞计数检测细胞增殖,用流式细胞仪分析细胞周期和活性氧（ROS）水平,Westernblot检测凋亡信号通路相关蛋白的表达。结果表明,10nmol／L硼替佐米联合50nmol／L阿糖胞苷对U937细胞有明显增殖抑制作用。两药联合协同诱导细胞凋亡。两药联合较单药处理能明显协同增加U937细胞ROS的水平,并能明显上调U937细胞中p-P38,p-JNK表达,下调p-ERK的表达。结论：硼替佐米联合阿糖胞苷协同诱导U937细胞凋亡．其机制可能与R0s的损伤导致JNK、P38通路的激活和ERK的下调,从而影响细胞线粒体途径有关。     

新型含氮双氢青蒿素二聚体对人白血病细胞株NB4-R1细胞凋亡的影响

目的：探讨新型水溶性含氮双氢青蒿素二聚体SM 1044对全反式维甲酸耐药急性早幼粒细胞白血病细胞株NB4-R1细胞凋亡的影响及其可能的机制。方法：流式细胞术检测SM 1044对细胞凋亡、线粒体跨膜电位以及细胞活性氧(ROS)水平的影响，Western blot检测SM 1044对MAPK(ERK、JNK)信号通路以及PML/RARα融合蛋白的影响和凋亡相关蛋白表达的变化。结果：SM 1044能够显著诱导NB4-R1细胞发生细胞凋亡以及线粒体跨膜电位丢失，同时能活化凋亡相关蛋白caspase-3、caspase-8、caspase-9以及抗多腺苷二磷酸核糖聚合酶；SM 1044可诱导NB4-R1细胞产生ROS;Western blot检测结果显示，SM 1044能够激活MAPK(ERK、JNK)信号通路的磷酸化，同时下调PML/RARα融合蛋白的表达。结论：SM 1044能够诱导全反式维甲酸耐药急性早幼粒细胞白血病细胞株NB4-R1细胞凋亡，其诱导凋亡可能与ROS/ERK以及ROS/JNK信号通路有关，此外，SM 1044也可通过下调PML/RARα融合蛋白诱导细胞凋亡。     

细胞间黏附分子 1 通过活化 MAPK 通路调节小鼠间充质干细胞向脂肪细胞分化简

本研究旨在探讨细胞间黏附分子-1（intercellular cell adhesion molecule-1,ICAM-1）调节小鼠间充质干细胞（mesenchymal stem cell,MSC）向脂肪细胞分化的分子机制.分别将小鼠ICAM-1重组逆转录病毒MIGR1-ICAM-1和空载体逆转录病毒MIGR1感染小鼠间充质干细胞系C3H10T 1/2细胞,获得稳定高表达ICAM-1的C3H10T 1/2细胞（MIGR1-ICAM-1/MSC）和对照组细胞（MIGR1/MSC）.通过Western blot检测P38,ERK和JNK通路的活化情况,观察MIGR1-ICAM-1/MSC和MIGR1/MSC向脂肪细胞的诱导分化.实验组加入P38、ERK及JNK 3种信号通路抑制剂后进行培养并观察其成脂肪分化情况.以原位油红染色观察脂滴,应用real-time PCR检测成脂分化关键转录因子C/EBPα和PPARγmRNA的表达水平.结果显示,ICAM-1过表达可活化MSC的P38、ERK及JNK通路;原位油红染色及real-time PCR检测结果显示对ERK通路活化抑制可导致MIGR1-ICAM-1/MSC的C/EBPα和PPARγ的mRNA表达水平上调,脂滴变大,脂肪数量增加（P＜0.01）;阻断P38通路后MIGR1-ICAM-1/MSC的C/EBPα和PPARγ mRNA表达水平下调,脂滴及脂肪细胞数量更小、更少（P＜0.01）.结论：ICAM-1可能通过活化ERK信号通路抑制MSC的成脂分化,通过活化P38通路维持小鼠MSC成脂分化能力.     

组织因子在移植物抗宿主病患者内皮损伤中的作用机制研究

8MAPK和JNK磷酸化增强,而磷酸化ERK无变化.p38MAPK和JNK阻滞剂可显著降低异基因CD4+和CD8+T淋巴细胞诱导HUVEC的TF表达.抗TF抗体和p38MAPK、JNK阻滞剂均可下调异基因T淋巴细胞诱导的HUVEC中VCAM-1、TNF-α、IFN-γ和IL-6的表达.结论 TF通过细胞内信号通路p38MAPK和JNK参与了GVHD导致的血管内皮细胞损伤和活化.     

Cdc37在多发性骨髓瘤中的表达及其参与骨髓瘤细胞增殖的研究

目的:探讨细胞分裂周期蛋白37(Cdc37)在多发性骨髓瘤(MM)中的表达及其对MM细胞增殖的影响。方法:采用实时定量PCR技术检测63例初治MM患者及8例正常人CD138+细胞中Cdc37 m RNA表达水平。采用慢病毒感染技术,下调MM细胞系NCI-H929细胞中Cdc37的表达水平,CCK-8法、软琼脂克隆形成实验检测Cdc37对MM细胞体外增殖能力的影响。建立NOD/SCID小鼠皮下成瘤模型,验证Cdc37对MM细胞体内增殖能力的影响。流式细胞术检测Cdc37对MM细胞周期的影响,蛋白免疫印迹法检测周期相关蛋白的表达变化和NF-κB信号通路的改变。结果:与正常人相比,Cdc37在初治MM患者CD138+细胞中显著高表达。采用sh RNA慢病毒感染技术下调NCI-H929细胞中Cdc37的表达水平,抑制了MM细胞在体内及体外的增殖能力。与对照组相比,NCI-H929-Cdc37 sh RNA细胞中G0/G1期细胞比例显著增加,细胞周期素cyclin D1的表达水平明显下调,而周期负向调控因子p21及其上游调控分子p53的表达明显上调。同时,NCI-H929-Cdc37 sh RNA细胞中NF-κB信号通路激活受抑。结论:Cdc37在初治MM患者中高表达,下调Cdc37可抑制MM细胞NCI-H929的增殖活性,诱导细胞周期阻滞于G0/G1期。其机制可能是抑制NF-κB信号通路的激活。     

基于IRAK4/ERK/p38信号通路雷公藤红素对多发性骨髓瘤细胞增殖和凋亡的影响

目的:探讨雷公藤红素对人多发性骨髓瘤细胞增殖和凋亡的影响,并揭示IRAK4/ERK/p38信号通路与雷公藤红素调控H929、ARP-1细胞增殖和凋亡的关系,探究雷公藤红素联合硼替佐米是否具有协同作用。方法:采用CCK-8法检测多发性骨髓瘤细胞株H929、ARP-1细胞经不同浓度雷公藤红素、硼替佐米以及二者联用后的细胞活力,并利用金氏公式判定协同药效。Annexin V/PI法检测H929细胞凋亡率和ARP-1细胞坏死率。蛋白免疫印迹法检测雷公藤红素对IRAK4/ERK/p38信号通路中关键蛋白和凋亡蛋白表达的影响。结果:雷公藤红素能够呈时间-浓度依赖性地显著抑制H929、ARP-1细胞的增殖(r=0.9018,0.9244),并诱导细胞的凋亡;与对照组比较,雷公藤红素能够明显上调H929、ARP-1细胞内PARP、cleaved caspase-3表达,下调p-IRAK4、p-ERK、p-p38表达。雷公藤红素、硼替佐米单用对H929、ARP-1细胞均有增殖抑制作用,而联合用药与单药相比,前者细胞存活率更低,凋亡率更高(P<0.05)。结论:雷公藤红素能抑制H929和ARP-1细...     

MAP Kinase cross talks in oxidative stress‐induced impairment of insulin secretion. Involvement in the protective activity of quercetin

Insulin secretion preservation is a major issue for the prevention or treatment of type 2 diabetes. We previously showed on β‐cells that quercetin (Q), but not resveratrol (R) or N‐acetyl cysteine (NAC), amplified glucose‐induced insulin secretion in a calcium‐ and ERK1/2‐dependent manner. Quercetin, but not resveratrol or NAC, also protected β‐cell function and hyperamplified ERK1/2 phosphorylation in oxidative stress conditions. As quercetin may interfere with other stress‐activated protein kinases (JNK and p38 MAPK), we further explored MAPK cross talks and their relationships with the mechanism of the protective effect of quercetin against oxidative stress. In INS‐1 insulin‐secreting β‐cells, using pharmacological inhibitors of MAPK pathways, we found that under oxidative stress (50 μm H₂O₂) and glucose‐stimulating insulin secretion conditions: (i) p38 MAPK phosphorylation was increased and regulated by ERK1/2 (positively) and JNK (negatively), although p38 MAPK activation did not seem to play any significant role in oxidative stress‐induced insulin secretion impairment; (ii) the JNK pathway appeared to inhibit both ERK1/2 activation and insulin secretion, although JNK phosphorylation was not significantly changed in our experimental conditions; (iii) the functionality of β‐cell in the presence of oxidative stress was closely linked to the level of ERK1/2 activation, (iv) quercetin, resveratrol, or NAC inhibited H₂O₂‐induced p38 MAPK phosphorylation. The preservation of β‐cell function against oxidative stress appears dependent on the balance between ERK1/2 and JNK activation. The protecting effect of quercetin appears due to ERK1/2 hyperactivation, possibly induced by L‐type calcium channel opening as we recently showed (Br. J. Pharmacol. 2013, 169, 1102–1113).     

联合抑制Notch2和MEK/ERK通路对胃癌细胞增殖的影响

目的探讨Notch2和MEK/ERK信号通路在胃癌细胞SGC-7901中是否存在交叉作用。方法采用体外化学合成的特异性针对Notch2的siRNA(Notch2siRNA)和丝裂原激活蛋白激酶(MEK)/细胞外信号调节激酶(ERK)信号通路的抑制剂PD98059,分别单独和联合处理体外培养的胃癌SGC-7901细胞,以转染阴性对照siRNA(control siRNA)细胞作为siRNA对照组,并设不给予任何转染的空白对照组。免疫印迹(Western Blotting)法检测磷酸化ERK1/2(p-ERK)1/2和Notch2蛋白的表达水平。比色法(MTT)检测癌细胞增殖抑制率。结果Notch2siRNA能降低蛋白Notch2的表达水平,并抑制癌细胞增殖[(38.26±1.82)%],而p-ERK的表达水平则较对照组增加。PD98059能降低p-ERK的表达水平,并抑制癌细胞的增殖[(30.05±3.16)%],Notch2水平则无明显变化,联合应用Notch2siRNA和PD98059能明显降低p-ERK和Notch2蛋白的表达水平,与Notch2siRNA或PD98059单独应用比较,显著抑制癌细胞增殖率,差异有统计学意义[(72.55±5.30)%,P0.01]。结论特异性抑制Notch2信号通路,且抑制MEK/ERK通路可进一步增强抑制Notch2通路的抗肿瘤增殖效果,提示MEK/ERK和Notch2 2条信号通路在胃癌SGC-7901细胞中存在交叉作用。     

Interleukin-1beta-induced transdifferentiation of renal proximal tubular cells is mediated by activation of JNK and p38 MAPK

Interleukin (IL)-1beta induces renal tubular epithelial cells to transdifferentiate to myofibroblasts, which express alpha-smooth muscle actin (alpha-SMA). To understand the signal transduction mechanisms involved in transdifferentiation, we examined the roles of mitogen-activated protein kinases (MAPKs) in IL-1beta-stimulated alpha-SMA expression and cell migration in the HK-2 human renal proximal tubular cell line. IL-1beta induced the transdifferentiation of renal proximal tubular cells, which was characterized by upregulated expression of alpha-SMA and increased cell migration. In addition, IL-1beta increased the activity of the three members of the MAPK family, ERK, JNK and p38 MAPK, in these cells. Both SP600125, a specific inhibitor of JNK, and SB203580, a specific inhibitor of p38 MAPK, suppressed the IL-1beta-induced expression of alpha-SMA and cell migration, but these effects were not observed with PD98059, a specific inhibitor of ERK. These results suggest that IL-1beta-induced HK-2 cell transdifferentiation is mediated, at least in part, through the activation of the JNK and p38 MAPK signaling pathways.     

Different Protein Tyrosine Kinases Are Required for B Cell Antigen Receptor–mediated Activation of Extracellular Signal–Regulated kinase,c-Jun NH2-terminal Kinase 1, and p38 Mitogen-activated Protein Kinase

B cell antigen receptor (BCR) cross-linking activates three distinct families of nonreceptor protein tyrosine kinases (PTKs): src-family kinases, Syk, and Btk; these PTKs are responsible for initiating downstream events. BCR cross-linking in the chicken DT40 B cell line also activates three distinct mitogen-activated protein kinases (MAPKs): extracellular signal–regulated kinase (ERK)2, c-jun NH₂-terminal kinase (JNK)1, and p38 MAPK. To dissect the functional roles of these PTKs in MAPK signaling, activation of MAPKs was examined in various PTK-deficient DT40 cells. BCR-mediated activation of ERK2, although maintained in Lyn-deficient cells, was abolished in Syk-deficient cells and partially inhibited in Btk-deficient cells, indicating that BCR-mediated ERK2 activation requires Syk and that sustained ERK2 activation requires Btk. BCR-mediated JNK1 activation was maintained in Lyn-deficient cells but abolished in both Syk- and Btk-deficient cells, suggesting that JNK1 is activated via a Syk- and Btk-dependent pathway. Consistent with this, BCR-mediated JNK1 activation was dependent on intracellular calcium and phorbol myristate acetate–sensitive protein kinase Cs. In contrast, BCR-mediated p38 MAPK activation was detected in all three PTK-deficient cells, suggesting that no single PTK is essential. However, BCR-mediated p38 MAPK activation was abolished in Lyn/Syk double deficient cells, demonstrating that either Lyn or Syk alone may be sufficient to activate p38 MAPK. Our data show that BCR-mediated MAPK activation is regulated at the level of the PTKs.     

Effects of florfenicol on LPS-induced nitric oxide and prostaglandin E₂ production in RAW 264.7 macrophages

Florfenicol, an antibiotic commonly used to treat infections, has previously been shown to modulate lipopolysaccharide (LPS)‐induced early cytokine responses by blocking the nuclear factor‐κB (NF‐κB) pathway. In this study, we investigated the effects of florfenicol on nitric oxide (NO) and prostaglandin E₂ (PGE₂) production as well as on inducible nitric oxide synthase (iNOS) and cyclooxygenase‐2 (COX‐2) expression in LPS‐stimulated murine RAW 264.7 macrophages. We also analysed the effects of florfenicol on mitogen‐activated protein kinase (MAPK) pathways. Florfenicol significantly inhibited LPS‐induced NO and PGE₂ production. Consistent with these observations, mRNA and protein expression of iNOS and COX‐2 were also inhibited by florfenicol in a dose‐dependent manner. Furthermore, phosphorylation of p38 and extracellular signal‐regulated kinase 1/2 (ERK1/2) in LPS‐stimulated RAW 264.7 cells was suppressed by florfenicol. However, c‐Jun N‐terminal kinase (JNK) phosphorylation remained unaffected. Using specific inhibitors of ERK and p38, we found that florfenicol may inhibit NO and PGE₂ mostly through ERK and p38 pathway. These results suggest that florfenicol inhibits NO and PGE₂ production in conjunction with an inhibition of iNOS and COX‐2 expression, at least partially via suppression of ERK1/2 and p38 MAPK phosphorylation.     

BAFF binds to the tumor necrosis factor receptor-like molecule B cell maturation antigen and is important for maintaining the peripheral B cell population

The tumor necrosis factor (TNF) family member B cell activating factor (BAFF) binds B cells and enhances B cell receptor-triggered proliferation. We find that B cell maturation antigen (BCMA), a predicted member of the TNF receptor family expressed primarily in mature B cells, is a receptor for BAFF. Although BCMA was previously localized to the Golgi apparatus, BCMA was found to be expressed on the surface of transfected cells and tonsillar B cells. A soluble form of BCMA, which inhibited the binding of BAFF to a B cell line, induced a dramatic decrease in the number of peripheral B cells when administered in vivo. Moreover, culturing splenic cells in the presence of BAFF increased survival of a percentage of the B cells. These results are consistent with a role for BAFF in maintaining homeostasis of the B cell population.     

ERK和P38信号转导途径对慢性髓系白血病细胞周期的调控作用

本研究探讨ERK和P38信号转导途径对慢性髓系白血病（CML）细胞周期的调控作用。以RT-PCR、Western blot和FCM方法分别检测CML患者白血病细胞和K562细胞中ERK、p38、cyclin D2、cyclin E、p27的mRNA表达及蛋白表达（其中ERK和P38为磷酸化ERK和磷酸化P38）及细胞周期分布,并分析其相关关系。结果表明：CML患者白血病细胞和K562细胞中ERK、P38、cyclin D2、cyclin E的mRNA表达和蛋白表达增高,P27的表达降低,且cyclin D2蛋白表达与cyclin E、ERK和P38蛋白表达呈正相关（P〈0.01）,与P27蛋白表达呈负相关（P〈0.01）。G0/G1期细胞减少,S期细胞增多,与对照组相比有显著性差异。结论：CML中P38、ERK mRNA表达和活性增加,激活下游的cyclin D2、cyclin E和P27等细胞周期调控因子,致使G0/G1期缩短,细胞快速通过G1/S转换点进入S期,加速细胞周期进程和细胞增殖,导致CML的发生。