CDC37 is a protein that is expressed in proliferative zones during embryonic development and in adult tissues, consistent with a positive role in proliferation and is required for cell division in budding yeast. CDC37 is though to play an important role in the establishment of signaling pathways controlling cell proliferation through targeting intrinsically unstable oncoprotein kinases such as Cdk-4, Raf-1, and src to the molecular chaperone Hsp9. Decreased Hsp9 expression can reduce the levels of microtubule-associated protein tau, whose overexpression may induce many diseases. CDC37 is considered as a co-chaperone that is classified to Hsp9's accessory proteins. It has been reported that suppression of Cdc37 destabilized tau, leading to its clearance, whereas cdc37 overexpression preserved tau.Cdc37 was found to co-localize with tau in neuronal cells and to physically interact with tau from human brain. Moreover, Cdc37 levels significantly increased with age.