Cantharidic acid is a hydrolysis product of cantharidin , an inhibitor of protein phosphatases first isolated from Chinese blister beetles. Cantharidic acid inhibits the protein phosphatases PP1 and PP2A with IC50 values of 0.6 and 0.05 μM, respectively, but does not affect PP2B or PP2C. Cantharidic acid is frequently used to study cellular processes that are regulated by reversible protein phosphorylation.
