A bacterial lacZ gene was inserted into the gene such that the endogenous gene promoter drives expression of beta-galactosidase. While high levels of RNA transcripts are detected in pancreas and kidney, moderate levels are found in many of the tissues tested. Beta-galactosidase expression from this allele is detectable in several organs examined, with most striking expression in brain, eyes, pancreas, kidney and testis. (J:101679)