A targeting vector was designed to insert a T2A oligopeptide that mediates ribosomal skipping (foot-and-mouth disease virus 2A from the insect Thosea asigna virus), a cre recombinase sequence, an SV40 polyA signal, and an frt-flanked neo cassette into the 3' untranslated region (after the translational termination site) of the cortistatin locus (Cort). This construct was electroporated into C57BL6/S129 hybrid embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient tetraploid blastocysts. Chimeric mice were bred with Actin-FLPe mice (on a C57BL/6 congenic background) to generate the colony and remove the neo selection cassette. The FLPe transgene has been bred out of the line.