Cofilin is a ubiquitous actin-binding protein required for the reorganization of actin filaments. It is a member of ADF (actin-depolymerizing factor)/cofilin family that is a key regulator of actin dynamics and essential for cellular motility,cytokinesis,and endocytosis. Cofilin activity is tightly regulated by phosphorylation and dephosphorylation. Phosphorylation at Ser3 can inhibit its activity,also causing translocation from the nucleus to the cytoplasm.