SAHA is highly effective in cell lines with p53 mutations, breast cancer, MDA-MB-231R280K, BT-474E285K, and prostate adenocarcinoma PC3p.K139fs*31, where the antiproliferative effect was present due to the increased expression of CDKN1A (cyclin-dependent kinase inhibitor 1A encoding p21), while, at the same time, CCND1 (cyclin D1) and TP53 expression levels decreased [85]. This evidence concerns the gene CCND1 and breast cancer.