Calyculin A is a natural, cell-permeable inhibitor of the serine-threonine protein phosphatases (PP) PP1 and PP2A (IC50s = 0.3-0.7 and 0.5-1 nM, respectively). It is without significant effect against PP2B, PP2C, and PP4. Through its effects on PP1 and PP2A, calyculin A has been shown to either promote or inhibit...

Calyculin A, a polyene phosphate, was initially isolated from the marine sponge Discodermia calyx. It is a very potent, cell-permeable PP-1 and PP-2 inhibitor (IC50: 2nM and 0.5-1nM respectively, and extremely specific for PP-1 and PP2A classes of protein serine/threonine phosphatase among other acidic, alkaline...