ERBB2 and cancer: Several Hsp90 clients are notorious oncogenes (Raf-1, Akt, cdk4, Src, Flt-3, hTert, c-Met, etc.), and five of them are clinically validated cancer targets: HER-2/neu, Bcr-Abl, estrogen receptor, androgen receptor, and VEGFR [7]–[10].