Bone morphogenetic protein-4-induced epithelial-mesenchymal transition and invasiveness through Smad1-mediated signal pathway in squamous cell carcinoma of the head and neck
a Department of Otolaryngology, Xiangya Hospital, Central South University, Xiangya Road, Changsha, Hunan, China b Department of Otolaryngology, The Second People’s Hospital of Wuxi, Nanjing Medical University, Wuxi, Jiangsu, China