We  recently started using the Dako cerb2 antibody. We use a 1 in 400
dilution without antigen retrieval. It generally works quite well. Known
positives stain strongly positive. However, I am concerned about false
positives. We recently had a case which stained weakly, but distinctly
positive. When this case was repeated at another centre It was completely
negative. We also find that we get some staining of normal breast glandular
epithelium. This staining is quite specific and not like the usual
background staining that one sees when the dilution is wrong. All our other
immuno stains work well. Does anyone have any suggestions? Thanks. Tom.