A 39 bp segment of the promotor, containing the homeodomain and the O/E-like binding sites, was replaced with a 17 bp segment from the Olfr155 promotor region and an IRES-taulacZ-ACNf cassette was inserted immediately following the endogenous stop codon. The ACNf cassette self-excised in the male germline leaving no neo sequence. (J:115911)