BRCA1 protein in frozen and FFPE sections of moderately differentiated, lobular carcinoma (MDA-lob) from patient no. 7. A. H&E stained frozen section of tumor. B. Consecutive section of the same tumor stained with mouse monoclonal AP16 antibody and biotinylated anti-mouse IgG and avidin-biotin-peroxidase detection system showed that many of the cells showed distinct, punctate nuclear staining of category (2); insert shows focal staining . C. Standard dilution of mouse IgG served as a negative control. D. H&E section of FFPE tissue from patient no.7. E. Consecutive section of the same tumor treated with pressure cooker antigen retrieval and stained with the MS110 antibody showed that many of the cells exhibited distinct nuclear staining (2); insert shows light staining. F. Consecutive control section of FFPE tissue without primary antibody. (×200) insert (×2000).