1Alpha,25-dihydroxyvitamin D(3) - not just a calciotropic hormone

1Alpha,25-dihydroxyvitamin D(3), the hormonal form of vitamin D(3), is widely appreciated to play a central role in calcium and phosphorous homeostasis. It is becoming increasingly clear, however, that the sterol also plays an important role in the regulation of cellular growth, central nervous system function, and immune responsiveness. In this review, I will highlight some of the mechanisms by which 1alpha,25-dihydroxyvitamin D(3) regulates cellular growth, alters central nervous system function, and immune function.