HIF1A and hepatocellular carcinoma: Related to this, while the genes encoding the HIF pathway proteins HIF-1α (HIF1A) and HIF1-β (ARNT) were found to be the two most essential for hypoxic survival in MHCC97L (HCC) cells (Bao et al., 2021), no HIF pathway genes were among the most essential genes identified from CRISPR-Cas9 deletion screens using K562 chronic myeloid leukemia cells (Jain et al., 2020), or U2OS osteosarcoma cells (Thomas et al., 2021).