Hsp-90 interacts with more than 200 proteins; many of these “client proteins” include AKT, BCR-ABL, NPM-ALK, BRAF, KIT, MET, EGFR, FLT3, HER2, PDGFRA, VEGFR, which are expressed in CML, CLL, lymphoma, AML, non-small-cell lung cancer, breast cancer, prostate cancer, and GIST [80, 81]. The gene discussed is FLT3; the disease is gastrointestinal stromal tumor.