CDKN1A and cancer: Similar to VPA, SAHA treatment of cancer cells resulted in inhibition of the cell cycle progression by decreasing expression of checkpoint regulatory proteins including cyclin-dependent kinases (CDKs) and cyclins, whereas increasing expression of cell cycle suppressors like p21 in ovarian carcinoma cells [32], esophageal squamous cancer cells [33], and breast MCF-7 cancer cells [34].