CEACAM5 and colorectal carcinoma: Earlier work from our laboratory has shown that the antibody PR1A3, which is specific for membrane-bound carcinoembryonic antigen (CEA, formally designated CEACAM5), elicits ADCC against CEA-positive CRC cell lines even in the presence of super-physiological levels of free CEA (Durbin and Bodmer, 1987; Durbin et al, 1994; Conaghan et al, 2008).