TGFA and hepatocellular carcinoma: It was verified that sorafenib upregulates HIF-2α through the hypoxic response switch from HIF-1α inhibition, contributing to the resistance of hypoxic HCC cells by activating the HIF-2α/transforming growth factor (TGF)-α/epidermal growth factor receptor (EGFR) pathway26 and increasing the expression of VEGF and cyclin D125.