The transgene consists of an MMTV promoter, a human ERBB3 cDNA, and the bovine growth hormone exon 5 and polyadenylation sequence. The MMTV promoter was used to overexpress the human transgene in lung and mammary glands of transgenic mice. Transgenic animals express human ERBB3 mRNA in lung, mammary gland, brain, intestine, thymus, liver, and spleen as determined by RT-PCR analyisis. (J:80974)