Figure 1: Specificity testing of 9A6. Members of the CEA family were expressed on BOSC cells after transient transfection with expression vectors containing either the cDNA of CEACAM1, 5, 6, 7 or 8. Recognition of CEACAM3 and 4 was tested on stably transfected HeLa (CEACAM3) and CHO cells (CEACAM4). Expression of the constructs was confirmed with monoclonal antibodies known to recognize the corresponding proteins (CEACAM1, 3, 4, 5 and 6: D14HD11; CEACAM7: CAC2; CEACAM8: 80H3; green curves). An irrelevant monoclonal antibody served as a negative control (black curves). For specificity testing, protein G-purified GM-9A6 was tested on all CEACAM transfectants. A positive signal was only obtained with CEACAM6-expressing cells (red curves).