The KOMP targeting vector (PRPGS00067_A_B09) introduced an FRTt site, beta-galactosidase cassette, loxP site, neomhycin resistance cassette, FRT site, and loxP site upstream of exon 2 in addition to inserting a loxP site downstream of exon 4. Cre-mediated recombination removed the selection cassette and exons 2 through 4. The beta-galactosidase reporter gene remains intact. (J:226931)