CD147 (Basigin) is a member of the immunoglobulin superfamily, with a structure related to the putative primordial form of the family. CD147 is a widely expressed membrane glycoprotein that plays pivotal roles in spermatogenesis, embryo implantation, neural network formation and tumor progression. It stimulates adjacent fibroblasts to produce matrix metalloproteinases (MMPS) and may target monocarboxylate transporters SLC16A1, SLC16A3 and SLC16A8 to plasma membranes of retinal pigment epithelium and neural retina. In vitro, CD147 promotes outgrowth of astrocytic processes.