PC4 and SFRS1 interacting protein 1, also known as PSIP1, is a protein which in humans is encoded by the PSIP1gene.
Psip1 is also known as LEDGF/p75 (Lens epithelium derived growth factor) based on its initial characterization. This is a misnomer as the protein is present in most tissues and has no direct role in the development of Lens epithelium. LEDGF/p75, a transcription coactivator, gained prominence as the host factor which assists HIV integration and is probably the only protein whose knock down severely affects the HIV integration levels (~ 9 fold). The interaction between HIV integrase and human LEDGF/p75 is a promising target for anti-HIV drug discovery.