A transgenic construct containing cre recombinase under the control of the tetracycline-responsive regulatory element (tetO) and a second transgenic construct containing rtTA, under the control of the human ACTA1, actin, alpha 1, skeletal muscle promoter were coinjected into fertilized (C57BL/6 X C3H)F2 mouse eggs. Founder line 102 was subsequently established. Female founder animals were bred to wildtype C57BL/6J mice. (J:159973)