ERBB2 and cancer: High HIF-1α protein expression in tumors reflects stabilization of HIF-1α protein due to the frequent presence of intratumoral hypoxia as well as increased synthesis of the protein caused by genetic alterations involving oncogenes (such as HER2/neu) and tumor suppressor genes (such as p53, PTEN, and VHL) and autocrine growth factor signaling in cancer cells [16], [17].