HSPB1 and cancer: Moreover, combined treatment of HSP90 inhibitor and SW15 synergistically enhanced cancer cell death in vitro and in vivo, depending on HSP27 expression and the presence of the normal dimerization site at Cys141, suggesting that addition of an HSP27 inhibitor with altered cross linking of HSP27 could overcome HSP90 inhibitor-mediated compensatory mechanisms such as increased expression of HSP27.