A vector containing a splice acceptor sequence-puromycin resistance gene, a CAG promoter, a floxed primary stop cassette, an FRT-flanked stop cassette, and EGFP-TeNT (tetanus toxin light chain) -SV40pA cassette was inserted into intron 1 via homologous recombination. Cre mediated recombination removed a stop cassette. Flp mediated recombination will result in the expression of the EGFP/TeNT gene. (J:210615)