MYC is also overexpressed in one third of breast cancers [259] and PIAS1 is essential for the viability of MYC-dependent breast cancer cells, with reduced proliferation of MYC-dependent MDA-MB-231 cell line observed when PIAS1 is depleted, which is not observed in MYC-independent MCF7 cells [60]. This evidence concerns the gene PIAS1 and breast cancer.