FKA treatments do not affect Skp2 expression at the transcriptional levels (data not shown), but down-regulates the protein expression of Skp2 and induces the accumulation of p27 protein, a Skp2 substrate, in prostate cancer cell lines in a dose and time manner (Fig. 2A and Supplementary Fig. 2). This evidence concerns the gene CDKN1B and Familial prostate cancer.