However, it seems likely that secreted HSP90, being a molecular chaperone, is able to directly interact with the secreted MMPs and such extracellular chaperoning enhances the proteinase activity aimed at local destruction of the extracellular matrix/connective tissue, thereby facilitating tumor cell migration, CSC niche formation, invasion, and metastasis occurrence. This evidence concerns the gene HSP90AA1 and neoplasm.