ESR1 and cancer: A small number of hypoxia-associated genes (APLN, HIF1A, and BNIP3), cancer stem cell (CSC) markers (CD24 and CD44), hormonal regulation (HR) genes (ESR1, PGR, and TFF1), other selected genes (PPARGC1A, ILK), and HKGs (RPL32, GUSB, TBP, OAZ1 and NONO) were also included in the panel.