A vector containing the P1 portion of the promoter from the rat Ggtp gene, mouse Agtr1a and the pA signal, as well as the human HPRT promoter, exon 1 and mouse Hprt exon 2 was inserted into ES cells with a deletion proximal to exon 3. Southern blot analysis confirmed recombination in ES cells. RT-PCR showed that the inserted sequence was expressed in transgenic kidneys. (J:91837)