The coordinate expression of the nuclear p53 protein, cytoplasmic intermediate filament vimentin (VIM) and membrane epidermal growth factor receptor (EGF-R) was significantly associated with oestrogen receptor immunocytochemical nuclear stain (ER-ICA) negative breast carcinomas. Twenty-three (51.1%), 26 (57.8%) and 27 (60%) of 45 ER-ICA -ve cancers were respectively p53 +ve, VIM +ve and EGF-R +ve; whereas of 151 ER-ICA +ve tumours 8 (5.3%) were p53 +ve (P less than 0.0001), 23 (15.2%) VIM +ve (P less than 0.001) and 40 (26.5%) EGF-R +ve P less than 0.001). Thirty-six of 45 (80%) ER-ICA -ve carcinomas were positive for at least one of the markers versus 55/151 (36.4%) ER-ICA +ve cases (chi 2 = 28.92, P less than 0.001). A prevalence of high grade carcinomas was found among p53 +ve, VIM +ve cases; the latter subset of tumours also had a larger mean diameter. These results suggest that ER -ve breast carcinoma cells display a coordinate expression of cell cycle-related proteins and marked changes of both the cytoskeleton and the membrane receptor repertoire.