The transgene construct was generated by fusing the codon-improved cre recombinase (icre) sequence with a nuclear localization signal, to the translation initiation codon of the Hmx3 (Nkx5-1) gene located in a bacterial artificial chromosome (BAC). An SV40 polyadenylation signal followed the cre sequence. This modified BAC was used to generated transgenic mice. (J:151793)