Protein phosphatase 1 regulatory subunit 26 (PPP1R26) interacts with and inhibits the phosphatase activity of protein phosphatase 1 (PP1) complexes []. The protein is widely expressed in multiple tissues in humans []. Although its exact biological function is not known, PPP1R26 may positively regulate cell proliferation, and has oncogenic characteristics - its expression in NIH3T3 fibroblasts has been shown to cause tumour development in nude mice [].