Hprt1^{tm1(Pbsn*-cre/ERT2)Jir}

A 500 bp composite promoter construct having two tandem androgen response elements fused to a short rat Probasin promoter fragment was placed upstream of a cre/ERT2 expression cassette. This construct was placed into a Hprt rescue vector (containing Hprt promoter sequence and the first three exons) and was used in recombination of ES cells containing a spontaneous deletion spanning the first two exons of Hprt. Clones undergoing homologous recombination were isolated by virtue of their resistance to HAT selection, which is mediated by Hprt expression. When founder mice were crossed to mice carrying cre-reporter alleles, cre expression was found to be specifically expressed in the prostrate epithelium and was strictly tamoxifen dependent. (J:144541)