LIM proteins, containing conserved LIM domains with zinc fingers, mediate protein-protein interactions. LIM kinase-1 (LIMK1) belongs to a subfamily with two N-terminal LIM motifs and a C-terminal kinase domain. LIMK1 is a serine/threonine kinase that regulates actin polymerization by phosphorylating and inactivating cofilin, an actin-binding factor. It is widely expressed during development and is involved in cellular processes related to cytoskeletal structure. LIMK1 also promotes axon growth and may play a role in brain development. Hemizygosity of LIMK1 is linked to impaired visuospatial cognition in Williams syndrome. Alternative splicing generates multiple transcript variants encoding distinct isoforms.