A cre recombinase gene, SV40 late polyA site, and an-FRT-flanked kanamycin cassette were introduced 3' of the Pdgfra promoter in mouse BAC RP23-116F7. The kanamycin cassette was excised from the vector and the linearized BAC was injected into C57BL/6 blastocysts. This strain was maintained on a C57BL/6 genetic background by the donating laboratory. (J:165545)