FKBP52 (FK506 binding protein 4) is a member of the immunophilin protein family that comprises intracellular protein effectors of immunosuppressive drugs,and it is known as a steroid receptor-associated protein. As a novel regulator of microtubule dynamics,FKBP52 is associated with the motor protein dynein and with the cytoskeleton during mitosis. FKBP52 is highly expressed in CNS regions susceptible to Alzheimer's,and plays a role in modulating toxicity of Abeta peptides. The protein can associate with the Tau function,and may help to decipher and modulate the events involved in Tau-induced neurodegeneration. In addition,FKBP52 is likely to play a role in growth and development of the male genitalia.