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