Growth factors are a group of proteins which stimulate the growth of cells. There are many times of growth factors including but not limited to BMPs, NGFs, BDNFs, EGFs, FGFs, CSFs, HGFs, LIFs, IGFS, PDGFs, TGFs, GDNFs, VEGFs, and SCFs. 

A fully extended dorsal root ganglion (DRG) growth cone growing on a laminin-coated tissue culture plate in te presence of beta-NGF