Protein kinases comprise a large group of encoded factors that regulate cellular processes by catalyzing the transfer of a phosphate group to a hydroxyl acceptor in serine, threonine or tyrosine residues. Myotonic dystrophy kinase-related Cdc42-binding (DMPK-like) kinases-a and b (MRCK-a, b) contain a cysteine-rich motif and a putative pleckstrin homology domain. MRCKs can phosphorylate nonmuscle myosin light chain and influences actin-myosin contractility (3,4). MRCK-a can phosphorylate and activate LIM kinases downstream of Cdc42, which leads to inactivation of ADF/cofilin and to Actin cytoskeletal reorganization. MRCK-a can also influence neurite outgrowth promoted by Cdc42 and Rac.