rck/p54, a DEAD-box RNA helicase, is closely associated with the basic modification of RNA molecules in the process of mRNA transport, RNA decay, and translation initiation. In the current study, Western blot analysis revealed that rck/p54 protein was ubiquitously expressed in mouse tissues. Interestingly, three different-sized rck/p54 proteins were detected by antibodies against mouse rck/p54, and these products were differentially expressed in the tissues. An immunohistochemical study revealed that rck/p54 was strongly expressed in basal cells of the crypt in the gastrointestinal tract and in neuronal bodies of the cerebral cortex, and was localized in epithelial cells of the convoluted tubules of the kidneys, suggesting that the heterogeneous rck/p54 may play pivotal roles in cells committed to become specialized in these tissues.