Sequence encoding a nuclear localization signal and cre recombinase was adjoined to regulatory elements of the mouse Atp4b gene (nucleotides -1035 through +24). The construct also contained a sequence fragment from the human growth hormone gene (GH1) (nucleotides +3 through +2150). The transgene was expressed in the progenitors of acid-producing parietal cells. Expression was not observed in gastric enteroendocrine cells.