GMFB, also known as GMF, belongs to the GMF subfamily of the larger actin-binding protein ADF family. This protein, which is phosphorylated following phorbol ester stimulation, is important for the nervous system. It causes brain cell differentiation, stimulates neural regeneration and inhibits tumor cell proliferation. Overexpression of GMFB in astrocytes has been shown to enhance brain-derived neurotrohic factor (BDNF) production. GMFB expression is increased by exercise, and the protein is crucial for exercise-induction of BDNF.