HSP90B2P and cancer: ex-HSP and EV-HSP play crucial roles in cancer progression by binding to cell surface receptors such as CD91 [low-density lipoprotein receptor-related protein (LRP1)/α2 macroglobulin receptor (A2MR)], promoting epithelial-mesenchymal transition (EMT), migration, invasion, heterogeneity, metastasis, CSC-like properties, and drug resistance in cancer cells and angiogenesis [26,27,28,29,30,31,32].