Recognition of CEA by MA39 antibody. A. Immunodetection of CEA in LoVo cells by MA39 scFv (left slide). The same slide preparation incubated with irrelevant anti-glucose oxidase (a protein not present in mammals) scFv antibody (anti-G.O., right slide). B. Biochemical patterns of the MA39 on purified CEA (lane 1) and LoVo cellular extract (lane 2). Lanes 3 and 4 show the reactivity of identical proteins with irrelevant anti-G.O. scFv. C. Staining of cryosections from human colon carcinoma xenograft in mouse. Commercially available anti-CEA antibody and irrelevant anti-G.O. antibodies were used as positive and negative controls, respectively.