CDKN1A and breast cancer: Similarly, Tu et al. [74] used ChIP-seq and RNA-seq approaches to further show that MYC represses the expression of tumor-suppressor genes, such as CDKN1A, GADD45A, and HMOX1, through interacting with G9A (EHMT2), a histone methyltransferase that causes H3K9 methylation and gene repression in breast cancer cells.