This transgene contains the human enhancer element hs653 -- which is flanked on human Chr 3 by the interleukin 20 receptor subunit beta (IL20RB) and SRY-box 14 (SOX14) loci -- followed by a mouse minimal Hsp68 promoter, the cre/ERT2 fusion gene, an internal ribosomal entry site (IRES), and a green fluorescent protein reporter gene. The fusion gene encodes Cre recombinase joined to a modified ligand-binding domain of the human estrogen receptor that preferentially binds tamoxifen or 4-hydroxytamoxifen, but not endogenous 17beta-estradiol; upon binding to tamoxifen, the cre/ERT2 protein is translocated to the nucleus.