A transgenic construct containing 9.5kb 5' regulatory sequence and first intron of the rat insulin 2 gene (RIP7) controlling the reverse tetracycline transactivator (rtTA), as well as the polyadenylation site sequence of the RIP7 gene was injected into fertilized (C57BL/6 X CBA)F2 mouse eggs. Founder line 2 with 10 copies of the transgene was established. When mice are crossed to transgenic mice carrying reporter genes, transgene expression is detected only in pancreatic islet beta cells.