LIM proteins, including LIM kinase-1 (LIMK1), contain LIM domains with two zinc fingers, likely mediating protein-protein interactions. LIMK1, part of a subfamily with two LIM motifs and a kinase domain, is a serine/threonine kinase that regulates actin polymerization by phosphorylating and inactivating cofilin. It is widely expressed during development and plays a role in cytoskeletal structure, axon growth, and brain development. LIMK1 hemizygosity is linked to impaired visuospatial cognition in Williams syndrome. Alternative splicing produces multiple isoforms of this protein.