Protein phosphatase 1 (PP1) is essential for cell division; and participates in the regulation of glycogen metabolism; muscle contractility and protein synthesis. Promotes nuclear envelope reassembly by targeting nuclear membrane vesicles to chromatin at the end of mitosis. Acts by dephosphorylating membrane proteins such as lamin B receptor (lbr) to regulate the binding of membrane proteins to chromatin (By similarity). {ECO:0000250}.