Effect of hydrogen peroxide and diphenylene iodonium on levels of EPAS-1 and HIF-1α. Immunoblots of whole-cell extracts (100 μg) from HeLa(B) cells with MoAb 190b (upper panels) and MoAb 28b (lower panels). (A) Cells were incubated in normoxia (N), 1% oxygen (H), 100 μmol/L DFO or 100 μmol/L cobalt chloride (CoCl₂). The presence (+) or absence (−) of 1 mmol/L hydrogen peroxide (H₂O₂) is indicated. (B) A similar experiment examining the effect of 5 μmol/L DPI.