CYP24A1 and neoplasm: Moreover, oncogenic CYP24A1 can promote tumor cell cycle progression by regulating genes involved in G0/G1 phase, such as cyclin A, c-Myc, p21, p27, and GADD45A 55, which is closely associated with the cell cycle arrest resulting from SIRT6 activation in CRC; these observations suggest that CYP24A1 could be a downstream target gene for SIRT6 responsible for cell cycle regulation.