BRCA1 and colonic neoplasm: Also, in human colon cancer cells, HIF-1α was shown to inhibit BRCA1 activity indirectly by counteracting C-MYC under hypoxic and normoxic conditions (Koshiji et al., 2004), while BRCA1 was found to enhance hypoxia-induced stabilization of HIF-1 (Kang et al., 2006).