PC4 and SF2 interacting protein (PSIP1) also known as Lens epithelium derived growth factor (LEDGF) is a multifunctional chromatin protein that has been implicated in regulation of homeotic genes, cell survival, cancers and autoimmune diseases.PSIP1 gene encodes two splice variants – a shorter isoform called p52 and a longer isoform called p75. The gene discussed is PSIP1; the disease is cancer.