ERBB2 and cancer: Heat Shock Protein 90α (HSP90α) has been considered to be a cancer therapeutic target for more than 20 years due to its prevalent overexpression in human cancer cells and its function as a chaperone that aids in the folding, maturation, and trafficking of several tumor-promoting proteins such as HIF-1α, mutated p53, STAT-3, CDK4, Akt, Bcr-Abl, and ErbB2/Neu [1,2,3].