BRCA1 and breast carcinoma: With immunofluorescence staining and confocal microscopy, we were able to detect BRCA1 sub-nuclear localization in frozen breast cancer tissue specimens and co-localization of BRCA1 and nucleolin in MCF7 (hemizygous for BRCA1 wild type), and HCC1937 (BRCA1 5382insC) cells.