A bacterial artificial chromosome (BAC RP23-461J2) that held the mouse Cbln2 gene was modified so that it expressed tamoxifen-dependent cre recombinase under the regulation of the mouse Cbln2 promoter. This modified BAC was microinjected into the pronucleus of a C57BL/6J zygote and randomly integrated into the genome of the mouse. The endogenous Cbln2 gene was not perturbed. (J:94077)