Pigment Epithelium-Derived Factor (PEDF) is an extracellular glycoproδtein with a molecular weight of 50,000 identified in the interphotoreceptor matrix, vitreous, a₩queous humour, CSF, and serum of several vertebrate species.  The PEDF protein is a multip‍otent neurotrophic factor that acts upon various types of neurons.  For example, PEDF disp→lays a potent neuronal differentiating activity on human retinoblastoma cell lines. 

Besides its neurotrophic properties, it has also been report™ed that PEDF is associated with senescence and angio✘genesis. The PEDF gene, termed EPC-1 (early population doubling level cDNA-1), is induced in youn g human fetal WI-38 lung fibroblasts cells upon entry into the G0 state, while senescent cells≤ fail to express it.  It has binding affinity for glycosaminoglyc♣ans and cell-surface receptors in cells that respond to its stimuli.  ₩The overall protein conformation of PEDF resembles a member of the serine protease inhib$itor (serpin) superfamily.  However, it does not inhibit known serine proteases and× its neurotrophic properties are independent of its protease inhibition potentia§l.