A construct was generated with a Tpbpa/Ada chimeric enhancer and Ada gene basal promoter ligated to the cre cDNA containing a nuclear localization signal (NLS). The 0.4 kb trophoblast specific protein alpha enhancer was cloned in reverse orientation (Tpbpar) with the 1.8 kb adenosine deaminase enhancer in forward orientation (Adaf); this chimeric enhancer was combined with the 0.8 kb basal Ada promoter (AdaP) in the transgenic vector . The linearized construct was injected into pronuclei of FVB zygotes. Six founders were obtained and all showed similar transgene expression patterns. Data from the mouse with the highest transgene copy number (line 5) is presented in the original reference.