Fig. 3

Effect of the five anti-EGFR sdAbs on inhibiting cell proliferation and promoting cell apoptosis. The inhibition of cell proliferation by the five anti-EGFR sdAbs (aEG1B4, aEG2C7, aEG2E12, aEG4D9 and aEG6B2) was tested by MTT assay on cancer cells A549 (a), MCF-7 (b) and DU145 (c). Cells were treated with different concentrations (0, 25, 50 and 100 µg/ml) of the anti-EGFR sdAbs. Two sdAbs (aVE201 and aHer2-13C1) were included as negative controls. Effect of the five anti-EGFR sdAbs on apoptosis was evaluated by apoptosis assay with cancer cells A549 (d, e), MCF-7 (f, g) and DU145 (h, i). Cells were incubated with 50 µg/ml of the anti-EGFR sdAbs. Annexin V-FITC was used to determine the percentage of cells undergoing apoptosis at an early stage, and propidium iodide (PI) was used to distinguish between viable and nonviable cells. Two sdAbs (aVE201 and aHer2-13C1) were included as negative controls. Data are shown as mean ± S.D. (n = 5). For a–c, *P < 0.05 and **P < 0.01 vs. the respective control (0 µg/ml); for e, g and i, *P < 0.05 and **P < 0.01 vs. PBS control