Wild-type PES1 promoted the expression of cyclin D1 in breast cancer cells, and the activation of cyclin D1 by PES1 was subject to regulation by SUMOylation, since the mutant PES1 that could not be SUMOylated had a weaker effect on the regulation of cyclin D1 expression (Figure 6). This evidence concerns the gene CCND1 and breast carcinoma.