This process is a physiological protection to avoid the hypercalcemia that can be induced by high levels of 1α,25(OH)2D3. It has been demonstrated that the expression of CYP24A1 is increased in prostate cancer and ovarian cancer cells after treatment with 1α,25(OH)2D3in vitro (15, 16). The gene discussed is CYP24A1; the disease is ovarian cancer.