Cofilin is a member of the ADF (actin-depolymerizing factor) protein family, that is involved in regulating actin dynamics in the growth cone. It binds to actin in a one-to-one molar ratio, and stimulates both the severing of actin filaments and depolymerization of actin subunits from the actin filament end. <br>Activated LIMK phosphorylates cofilin on conserved serine 3 (Ser3/S3), located near the actin binding site. After phosphorylation cofilin is inactive and looses its affinity for actin and releases from G-actin monomers. Now the ADP-actin monomers are free and can exchange ADP with cytoplasmic ATP and they are ready for reincorporation at the barbed end of the a growing filament.