The targeting construct consisting of the bicistronic Aldh1b1/P2A/CreERT2 transgene followed by the FRT-PGKneo- pA-FRT selection cassette was inserted in the endogenous Aldh1b1 locus to replace the coding region of mouse Aldh1b1 gene. The neo selection cassette was removed by Flp recombinase. (J:280398)