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Abstract

A DNA fragment distinct from the epidermal growth factor receptor (EGF-R) and erbB-2 genes was detected by reduced stringency hybridization of v-erbB to normal genomic human DNA. Characterization of the cloned DNA fragment mapped the region of v-erbB homology to three exons with closest homology of 64% and 67% to a contiguous region within the tyrosine kinase domains of the EGF-R and erbB-2 proteins, respectively. cDNA cloning revealed a predicted 148 kd transmembrane polypeptide with structural features identifying it as a member of the erbB family, prompting designation of the new gene as erbB-3. It was mapped to human chromosome 12q11-13 and was shown to be expressed as a 6.2 kb transcript in a variety of normal tissues of epithelial origin. Markedly elevated erbB-3 mRNA levels were demonstrated in certain human mammary tumor cell lines. These findings indicate that increased erbB-3 expression, as in the case of EGF-R and erbB-2, plays a role in some human malignancies.

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First Claim