protein phosphatase type 2A complex PP2A-pi cellular_component protein phosphatase 2 complex PP2A complex A protein complex that has protein serine/threonine phosphatase activity that is polycation-stimulated (PCS), being directly stimulated by protamine, polylysine, or histone H1; it constitutes a subclass of several enzymes activated by different histones and polylysine, and consists of catalytic, scaffolding, and regulatory subunits. The catalytic and scaffolding subunits form the core enzyme, and the holoenzyme also includes the regulatory subunit. GO:0000159 PP2a-protector protein serine/threonine phosphatase complex