HSP90AA1 and cancer: The inhibition of HSP90 in MCF-7 and SKBr-3 cells results in the degradation of AKT,313 further downregulating the activity of the PI3K/AKT pathway, which controls cell functions and many aspects of cell physiology.314 Similarly, inhibiting HSP90 expression decreases abundance of newly synthesized CDK4,315 which is a critical mediator of transition of cells to S phase and helps cancer cells to grow and survive.316 In addition, RAF1 kinase is associated with HSP90, an important part of the mitogen-activated protein kinase (MAPK) pathway that governs several crucial cellular processes.