Figure 5: Binding ability of immunotoxin to recombinant His-EpCAM and natural EpCAM. (a) Recombinant HIS-EpCAM protein was coated on 96-well plates (5 μg/mL). The binding of the immunotoxin to His-EpCAM was detected by ELISA. The value was analyzed by an unpaired Student’s -test. ∗∗ value was less than 0.05. (b) HHCC cells were collected and stained with primary antibody (biotin labeled immunotoxin, biotin labeled 2A9, or biotin labeled isotype control antibody) at a concentration of 5 μg/mL and FITC labeled avidin (1 : 50) as the secondary antibody. Fluorescence was detected by BD FACS Calibur. The mean fluorescent intensity was measured by FlowJo software.