c-erbB3 expression in breast tumour derived cell line

The c-erbB3 protein is a type 1 growth factor receptor. mRNA for c-erbB3 is expressed in several breast cancer cell lines and c-erbB3 protein has been detected by immunocytochemical staining in primary breast cancers. The relationship between protein expression and mRNA expression has not, however, been explored in detail. In this report we have used immunoprecipitation, Western blotting, immunocytochemistry, ELISA and FACS to assess the prevalence and level of c-erbB3 protein expression and its concordance with mRNA levels estimated by Northern blotting, in a series of breast cancer cell lines. The protein was found at low levels, consistent with the reported lack of the c-erbB3 gene amplification, and expression was generally proportional to the level of mRNA.