ESR1 and breast cancer: Other somatic genes that are implicated in signal transduction includes APC, ARID1A, ARID2, ASXL1, BAP1, KRAS, MAP2K4, MLL2, MLL3, NF1, SETD2, SF3B1, SMAD4, and STK11. Moreover, there other types of somatic genes that recently assigned with breast cancer pathogenicity are ARID1B, CASP8, MAP3K13, MAP2K13, NCOR1, SMARCD1, and CDKN1B.  In addition, the presence or absence of some specific proteins including estrogen receptors (ER), progesterone receptors (PR), and human epidermal growth factor receptor-2 (HER2) (8).