In contrast, Cdc37 functions as a kinase-specific cochaperone, recruiting a distinct subset of Hsp90 clients—primarily protein kinases, including many that drive malignant transformation and tumor progression such as Akt, Cdk4, Raf, and HER2.13,32 Disrupting the Hsp90–Cdc37 interface allows for preferential destabilization of these oncogenic kinase clients while largely sparing non-kinase clients.13,18 This targeted mechanism yields a more favorable therapeutic index and reduces collateral damage to normal cells. The gene discussed is CDK4; the disease is neoplasm.