CDKN1A and neoplasm: In addition, 1,25(OH)2D3 could suppress mitosis by increasing the expression levels of p27/Kip1 and p21/Waf1, inhibiting the activity of cyclin-CDK complex, promoting dephosphorylation of Rb protein, decreasing the transactivation of E2F, and then resulting in the tumor cells stagnated in G0/G1 stage [36].