Effect of MAb 2B2 recognizing the C-22 P0 epitope on colon adenocarcinoma cells. Panel A. Cells growth was assessed by sulforhodamine B assay. SW260 and HT29 cells were treated with MAb 2B2 at different concentrations (20, 5, 1 μg/ml). The antibody UPC10 was used as control (20 μg/ml). The results are the mean of three independent experiments (**p < 0.01, ***p < 0.001). Panel B. Trypan blue exclusion test was performed to determine the percentage of cell death of SW260 and HT29 cells treated with MAb 2B2 at different concentrations (20, 5, 1 μg/ml) or with the antibody UPC10 (20 μg/ml). The results are the mean of three independent experiments (***p < 0.001). Panel C. In situ detection of apoptosis. Induction of apoptosis in SW260 and HT29 cells, as assessed by immunolabeling with an anti-activated caspase-3 antibody, after treatment with MAb 2B2 (20 μg/ml) or UPC10 (20 μg/ml) for 48 hours or, as positive control, with staurosporine (1 μM) for 16 hours. Nuclei were counterstained with Hoechst.