We report the isolation and characterization of a serine/threonine kinase expressed during rat pancreas development. This kinase was cloned as part of a general screen using degenerate oligonucleotides to map expression of kinases and receptors during the course of pancreatic development. Sequence analysis showed it to be a member of the ste20-like serine/threonine kinase family. Northern blotting analysis against both fetal and adult tissues showed two transcripts, one of 2 kb and the other of 4 kb. The ratio of transcript expression varied with the tissue. In situ hybridization analysis showed that this gene is expressed in the early gut and pancreatic epithelium. By embryonic Day 15, the transcript is localized to cells that will eventually become exocrine in nature. In situ hybridization analysis also demonstrated high levels of expression in the choroid plexus, the developing myocardium, kidney, CNS, dorsal root ganglia, and testes. In addition, a search of the EST database revealed a related human kinase not previously described.