ERBB2 and breast neoplasm: In contrast to previously described mechanisms of growth factor-regulated HIF-1α, which involves perturbations to post-translational regulation and protein stability [24, 25], this HER2-driven increase in HIF-2α was found to occur at the level of transcription and coincided with increased gene expression levels of the HIF2A gene seen in the HER2-positive subtype in a large meta-analysis of breast tumours.