Early work showed that heat shock proteins gp96, Hsp90, Hsp70, and calreticulin could function as potential adjuvants to stimulate DC antigen cross-presentation and maturation through the CD91 receptor [33], but Hsp90α was more recently found to also stimulate tumor proliferation and metastasis through binding to cancer cell surface CD91 and be positively correlated with tumor malignancy in cancer patients [34–36]. This evidence concerns the gene HSP90AA1 and cancer.