Grade III and IV brain tumors (up to 63%) evidence the presence of an alteration in one of four genes, including PIK3CA (Phosphatidylinositol-4,5-Bisphosphate 3-Kinase Catalytic Subunit Alpha), PIK3R1 PTEN, and EGFR in PI3/Akt signaling pathway [54], whereas these genes are dependent on the Hsp90 clients, such as mutant EGFRvIII and other essential kinases [43]. The gene discussed is PIK3CA; the disease is brain neoplasm.