A transgenic construct was designed with the CMV enhancer/chicken beta-actin promoter, loxP-flanked STOP sequence (beta-geo reporter followed by SV40 polyadenylation signal), and a mouse Pth2 cDNA. When bred to mice expressing Cre recombinase expressing mice in specific tissues, the STOP sequence (and beta-geo) is removed allowing expression of Pth2 in Cre-expressing cells. (J:138142)