EPAS1 and breast carcinoma: Notably, at the 11q13.3 locus, strong HIF1A and EPAS1 ChIP-seq peaks overlapped the risk variants in the RCC cell line 786-O under hypoxic conditions (1% O2), but not in MCF-7 breast cancer cells8 or normal renal HK-2 cells under normoxic conditions (20% O2), consistent with prior reports (Fig. 2).