Comparison between MA39 and E8 antibodies. A. Recognition of metastatic melanoma cells expressing CEA by MA39 and maturated E8 scFv antibodies. Significant fluorescence shift indicates difference in affinity of two single-chain antibodies. B. Western blot with serial dilutions of CEA protein was stained by using original MA39 and maturated E8 scFv antibodies. The membranes were developed with secondary anti-FLAG AP-conjugated antibody.