HSP90AA1 and cancer: Such proteins have been called “client” proteins and the list includes Akt, RIP, Bcr-Abl (specifically in K562 cells), etc. Therefore, when Hsp90 is either destabilized due to the action of geldanamycin [4,36,37] or cleaved by an oxidative attack [20,21], its chaperone function is lost, client proteins are then degraded in the proteasome disturbing cellular equilibrium and ultimately causing cancer cell death.