Based on limited published evidence, PPP4R1 encodes a regulatory subunit of protein phosphatase 4 complex involved in signal transduction and protein phosphorylation regulation. UniProt annotations indicate PPP4R1 participates in merkel polyomavirus-mediated inhibition of NF-κB signaling by bridging viral small tumor antigen with NEMO. The protein localizes to the cytoplasm and exhibits protein binding and phosphatase regulator activities. In breast cancer, PPP4R1 expression is downregulated, particularly in luminal B subtype tumors 1, suggesting potential tumor suppressor functions on chromosome 18.