The CAG promoter (chicken beta-actin promoter with CMV enhancers) was used to drive expression of a FLPe gene with a nuclear localization signal. Five founder lines were established (lines 16, 32, 36, 37 and 41) with lines 16, 32 and 36 exhibiting 100% recombination when crossed to a mouse containing an frt-flanked allele; 10/11 mice of line 37 showed recombination. Mosaicism was noted in 2/9 of line 16 and in 1/8 of line 32 double transgenic mice. # is used when no line is specified.