LIM kinases are serine protein kinases with a unique combination of two N-terminal LIM motifs, a central PDZ domain, and a C-terminal protein kinase domain. LIMK1 is one of the downstream targets of PAK1 and is activated through phosphorylation by PAK1 on T508 within its activation loop (Edwards et al. 1999, Aizawa et al. 2001). LIM-kinase is responsible for the tight regulation of the activity of cofilin (a protein that depolymerizes actin filaments) and thus maintains the balance between actin assembly and disassembly. Phosphorylated cofilin is inactive, resulting in stabilization of the actin cytoskeleton.