Key regulator of protein phosphatase 1C (PPP1C). Mediates binding to myosin. As part of the PPP1C complex; involved in dephosphorylation of PLK1. Capable of inhibiting HIF1AN- dependent suppression of HIF1A activity. {ECO:0000269|PubMed:18477460; ECO:0000269|PubMed:19245366; ECO:0000269|PubMed:20354225}.