May play a role in the regulation of cell morphology and cytoskeletal organization (By similarity). Binds to F-actin and exhibits pH-sensitive F-actin depolymerizing activity. Required for formation of the cleavage furrow during cytokinesis. Cellular localization varies throughout development and may be related to phosphorylation levels. Shows diffuse cortical cytoplasm localization in oocytes, with membrane-association increasing after fertilization, particularly in the vegetal hemisphere. Expressed diffusely in both animal and vegetal hemispheres of the oocyte. During cleavage, expression accumulates around the cleavage furrow, along the vegetal membrane, and later in the midbody. Strongly expressed in the animal hemisphere during blastula stages, with most cells showing expression by gastrulation. By stage 17, expression is highest in cells of the developing neuroectoderm, and at stage 24 the notochord, neural tube, neural crest, somites and some cells of the archenteron show high expression. By stage 35, expression has declined in the notochord, but remains in the neural tube, epidermis and a layer of cells in the archenteron. Also highly expressed in the retina and neuronal cell bodies at the base of the cement gland but not the cement gland itself. At stage 38, expression is widespread, being highest in the nervous system and retina. In the adult, expression is high in the brain, heart, oocyte, stomach, and low in skeletal muscle. Expressed both maternally and zygotically. Maternal expression is gradually replaced with zygotic expression between the morula (stage 5) and tadpole (stage 34) stages. Inactive when phosphorylated. Phosphorylation levels vary during development. Oocytes contain only the phosphorylated form, and 80-95% of cfl1 protein is phosphorylated in unfertilized eggs. Rapid dephosphorylation occurs within 30 minutes after fertilization. Phosphorylation levels increase again between the morula and blastula stages (5-8 hpf) and then decrease again as gastrulation approaches. Dephosphorylated by pdxp (By similarity). Belongs to the actin-binding proteins ADF family.