LIM kinase-1 (LIMK1; EC 2.7.11.1) and LIM kinase-2 (LIMK2) are regulated by several upstream signaling pathways, principally acting downstream of Rho GTPases to influence the architecture of the actin cytoskeleton by regulating the activity of the ADF/cofilin family of actin binding and filament severing proteins cofilin1, cofilin2 and destrin. LIM kinases have a unique organization of signaling domains, with two amino-terminal LIM domains (each containing double zinc finger motifs), adjacent PDZ and proline/serine (P/S)-rich regions, followed by a carboxyl-terminal kinase domain. The LIM domains have been shown to play an important role in regulating kinase activity and likely also contribute to LIMK function by acting as sites of protein-to-protein and possibly protein-to-DNAinteractions.