In human primary prostate epithelial cells that expressed CYP27B1, low concentrations of 25(OH)D3 suppressed cell growth.(27) In prostatic cancer cells lacking CYP27B1, 25(OH)D3 failed to demonstrate antiproliferative action.(28) There are several mechanisms mediating the antiproliferative effects of 1,25(OH)2D3. Here, CYP27B1 is linked to prostate cancer.