Recombination mediated cassette exchange (RMCE) into Nkx2-2tm1Suss inserted nucleotide substitutions that result in several amino acid substitutions in the tinman (TN) domain (TGFSVKDILDLP to TGFAAAAIVDLP). An FRT-flanked neo cassette used for selection was removed by flp-mediated recombination. (J:177838)