Fig. 4. ErbB3 is essential for increased HIF1α stabilization in HNSCC.

a Protein lysates taken from larger ( ≥ 12 mm, n = 10) compared to smaller ( ≤ 6 mm, n = 3) tumors show that EGFR and ErbB3 are co-upregulated coincident with HIF1α stabilization in larger tumors. b Protein lysates from conditionally reprogrammed cells (Hoc6) exposed to CoCl₂ show that two-hour pre-treatment with anti-ErbB3 antibody (left panel, n = 3) but not Cetuximab (right panel, n = 3) suppresses cobalt chloride-dependent HIF1α stabilization, which is maximal at three hours. Relative HIF1α levels in control vs. treatment groups were quantified by photodensitometry after normalization to actin