A targeting plasmid containing the porcine teschoviral 2A cleavage sequence linked to Cre recombinase and a Frt-flanked neomycin resistance gene replacing the stop codon of the Calcr gene in a bacterial artificial chromosome (RP24-193M22) was used for embryonic stem cell targeting. Chimeric animals generated were mated to Flp-deleter mice to remove the neomycin selection cassette. (J:260503)