Pigment epithelium-derived factor (PEDF) also known as serpin F1 (SERPINF1), is a multifunctional secreted protein that has anti-angiogenic, anti-tumorigenic, and neurotrophic functions. Found in vertebrates, this 50 kDa protein is being researched as a therapeutic candidate for treatment of such conditions as choroidal neovascularization, heart disease, and cancer.[5] In humans, pigment epithelium-derived factor is encoded by the SERPINF1 gene. PEDF has a variety of functions including antiangiogenic, antitumorigenic, and neurotrophic properties. Endothelial cell migration is inhibited by PEDF. PEDF suppresses retinal neovascularization and endothelial cell proliferation. The antiangiogenic residues 24-57 were shown to be sufficient at inhibiting angiogenesis. PEDF is also responsible for apoptosis of endothelial cells either through the p38 MAPK pathway or through the FAS/FASL pathway Antiangiogenic function is also conferred by PEDF through inhibition of both VEGFR-1 and VEGFR-2. The antitumorigenic effects of PEDF are not only due to inhibition of supporting vasculature, but also due to effects on the cancer cells themselves. PEDF was shown to inhibit cancer cell proliferation and increase apoptosis via the FAS/FASL pathway. VEGF expression by cancer cells is inhibited by PEDF. PEDF also displays neurotrophic functions. Retinoblastoma cells differentiate into neurons due to the presence of PEDF. Expression of PEDF in the human retina is found at 7.4 weeks of gestation, suggesting it may play a role in retinal neuron differentiation.