Molecular and functional characteristics of erbB2 in normal and cancer breast cells.

The expression pattern of erbB2 and its transmembrane polymorphisms (Ile654Val and Ile655Val) were investigated in a panel of human normal and neoplastic breast cell lines to evaluate whether the expression pattern was affected by changes in the gene structure. At least two peptides of lower molecular mass forms (95 and 68 kDa) than the holoreceptor (185 kDa), comprehensive of the tyrosine kinase domain, were detected in all cells. Both peptides were also phosphorylated, suggesting a functional role in signal transduction. The presence of the polymorphisms found in two cell lines was unrelated to the expression of the lower molecular mass proteins.