This transgene consists of the mouse mammary tumor virus long terminal repeat (MMTV LTR), 5'-untranslated region from the HaSv, sequences encoding oncogenically mutated (glycine to valine at codon 12) human Kirsten (Ki)-rasB, and SV40 polyadenylation sequence. Highest level of transgene expression is in mammary tissue and no expression is seen in the kidney, liver or spleen. (J:77272)