This transgene contains the coding sequence for Cre recombinase, followed by a polyadenylation signal to terminate the fusion transcript immediately after the recombinase gene, inserted into the mouse genomic bacterial artificial chromosome (BAC) RP24-285K21 at the ATG transcription initiation codon of the retinol binding protein 4, plasma gene so that expression of the recombinase is driven by the regulatory sequences of the mouse gene.