Calyculin A

Calyculin A ((-) -Calyculin A), a toxicant in the Japanese marine sponge CDiscodermia calyxC, is a selective and potent inhibitor of protein phosphatase 1 (PP1) and protein phosphatase 2A (PP2A), inducing hyperactivation of cryopreserved bovine spermatozoa and inhibiting radiation-induced gammaH2AX DNA repair disease in human lymphocytes. gammaH2AX DNA repair foci in human lymphocytes.