PPP3CC and Infertility: Furthermore, we did not completely exclude the role of FKBP12 in FK506-induced infertility, since the complex of FK506-FKBP12 was also able to pull down some specific PPP3CC/PPP3R2 in the testes in our study, suggesting that the high level of intracellular FKBP12 might overcome the low affinity to PPP3CC/PPP3R2 in testes to make a certain contribution to FK506-induced calcineurin inhibition.