The allele was generated by inserting a 2A-CreER expression cassette in-frame before the STOP codon of the Btg2 gene. The targeting vectors generated using BAC clones from the RPCI-23&24 library were electroporated into a 129SVj/B6 hybrid ES cell line (v6.5). The Resulting ES cell clones were used for tetraploid complementation to obtain male heterozygous mice. (J:323692)