Phosphorylation of PP1α by cdc2 kinases in NIH-3T3 cells inhibits PP1α phosphatase activity in a cell cycle–dependent manner38, and phosphorylation of DARPP-32 at the T34 position leads to DARPP-32–mediated phosphorylation and inactivation of PP1α in neurons and cancer cells24,39. Here, PPP1CA is linked to cancer.