ERBB2 and cancer: To identify potentially actionable therapeutic gene targets for BC subtypes, we subsequently interrogated the cancer genes currently listed in the OncoKB precision oncology knowledge base [24], and identified GATA3, CCND1, ESR1, and ELP2 (for HR+), ERBB2, and CDK12 (for HER2+), and SOX9, HMGA1, ATP1A1, CAD, and PPP1CB (for TNBC) to be known cancer genes, Fig. S4.