It was confirmed that only isoform α of Hsp90 (and not β) played extracellular role in cancer cell invasiveness and tumor metastasis by matrix metalloproteinase-2 activation and tumor angiogenesis induction (Eustace et al. 2004; Sims et al. 2011; Song et al. 2012). This evidence concerns the gene HSP90AA1 and cancer.