PAK4 and breast cancer: We selected 26 genes (KIF22, CALM1, TRIAP1, AKT1, ANK3, ANKLE2, CHFR, CCDC8, CCNO, CREBBP, CTDSP2, ESR1, FGFR3, FOXA1, HTT, JTB, MAP4K1, MSTO1, MTA3, PAK4, PAK6, RECQL5, SMARCD3, STRADA, TJP3, and XPC) from 3728 HR+ breast cancer-related genes, focusing on those that were highly expressed in only the three HR+ breast cancer cell lines (Figure 1a).