A cre/ERT2 fusion protein was inserted into a BAC clone (RP23-279P6) containing 200kb sequences including the transcriptional regulatory elements of the Alb (albumin) and Afp (a-fetoprotein) genes in their original chromosomal arrangement. Recombination inserted the CreERT2 cassette within Alb exon1, thereby disrupting Alb coding sequences on the BAC but preserving the promoter and relevant 5 regulatory elements. The expression is restricted to the liver only with tamoxifen-inducible activation. (J:317522)