PHF1 (PHD protein finger 1), also known as polycomb-like protein 1 or hPCI1, is a 567 amino acid member of the PHD finger protein family. Members of the PHD finger protein family function as transcriptional regulators that affect gene expression by modulating chromatin structure. With a subcellular localization to the nucleus, PHF1 is widely expressed in tissues, with high expression in pancreas, heart and skeletal muscle and low expression in liver, lung, kidney, brain and placenta. PHF1 contains 2 PHD-type zinc finger domains, which may contribute to the transcriptional activity of PHF1. PHF1 is thought to interact with ENX-1, a component of PRC2 (polycomb repressive complex 2), increasing the gene silencing activity of PRC2. PHF1 exists as two isoforms produced by alternative splicing.