GMF-? (glia maturation factor, ?), also known as GMFG, is a 142 amino acid protein that belongs to the GMF subfamily of the larger Actin-binding protein ADF family. GMF-? is expressed predominantly in lung, heart and placenta.GMF-? is considered a candidate regulatory growth factor protein, mediating both paracrine and autocrine cell-cell interactions. GMF-? is phosphorylated at N-terminal serine, and its phosphorylation is enhanced by coexpression of dominant active Rac 1 and Cdc42. GMF-? expression is significantly increased in a cardiac ischemia/reperfusion model where inflammation and angiogenesis take place actively. As a regulator of Actin-based cellular functions, GMF-? may provide a novel approach to modulate the pathophysiology of cardiovascular diseases. GMF-? is primarily found in proliferative and differentiative organs.