An allele encoding a tissue-specific and ligand-dependent recombinase was generated by adjoining cre recombinase/modified estrogen receptor (ESR1) fusion sequence to 5.5 kb of the transgelin promoter and regulatory region. The ESR1 sequence contained engineered missense mutations at positions 400, 543, 540 which substituted the ability to bind the endogenous ligand with the ability to bind tamoxifen (J:79835). The Tagln promoter directed expression in smooth muscle cells. Transgenic expression was detected in smooth muscle tissue but was characterized as being low and mosaic. Recombination was tamoxifen-dependent.