PIAS1 and breast cancer: High level of the PIAS1 expression was also observed in breast cancer, and the knockdown of PIAS1 inhibited tumor growth in vivo. A subset of clinic-related genes such as cyclin D2, estrogen receptor, and breast tumor suppressor WNT5A is silenced by PIAS1 through histone modification and DNA methylation which indicates that PIAS1 can regulate tumorigenesis by selectively silencing genes [130].