CPPED1, also known as Serine/threonine-protein phosphatase 6 regulatory subunit 2, is a crucial regulatory protein involved in cellular signalling pathways. Primarily located in the cytoplasm and nucleus, CPPED1 functions as a regulatory subunit of protein phosphatase 6 (PP6), which belongs to the PPP family of serine/threonine phosphatases. It plays a vital role in modulating PP6 activity, essential for processes such as cell cycle progression, DNA damage response, and protein degradation. By interacting with PP6, CPPED1 helps regulate substrate specificity and the enzyme’s subcellular localisation.