CYP27A1 and cancer: In the present study, we evaluated whether OCDO and its precursors can undergo a 27-hydroxylation in cancer cells expressing CYP27A1 and compared the proliferative properties of 27H-OCDO ((25R)-cholestane-6-oxo-3β,5α,26-triol) on ER(+) and TN BC cells with OCDO and 27HC.