BRCA1 protein in frozen and FFPE sections of poorly differentiated adenocarcinoma (PDA) from patient no. 13 with a BRCA1 mutation (185delAG). A. H&E stained frozen section of the tumor. B. Consecutive section of the same tumor stained with rabbit polyclonal K-18 antibody and anti-rabbit IgG and avidin-biotin peroxidase detection system. Many of the cells exhibited diffuse nuclear staining (2), and insert shows diffuse staining. C. Consecutive section of the same tumor incubated with control rabbit IgG shows no appreciable staining. D. H&E section of FFPE tissue from patient no.13. 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 weak nuclear staining (1), and insert shows unstained nuclei. F. Consecutive control section of FFPE tissue without primary antibody. (×200) insert (×2000).