This transgenic construct encodes a tamoxifen-inducible cre recombinase protein. A human SERPINA1 promoter was adjoined to a sequence encoding a fusion protein consisting of cre recombinase and a mutated human estrogen receptor ligand-binding domain, to drive expression in hepatocytes. The ligand-binding domain possesses a substitution mutation at position 521, converting the region from an estradiol binding domain to a tamoxifen binding domain. In situ hybridization and immunohistochemical analysis showed expression in 40% to 50% of hepatocytes.