May increase cell susceptibility to TNF-induced apoptosis. Belongs to the protein phosphatase inhibitor 1 family. A report observed N-glycosylation at Asn-89 (PubMed:19139490). However, as the protein is not predicted to localize in an extracellular compartment of the cell, additional evidence is required to confirm this result. Was shown to be an inhibitor of protein-phosphatase 1, to promote cell growth and cell cycle progress at the G1/S transition and to interact with PPP1CB (PubMed:18310074). The article has later been withdrawn by the authors.