FIG. 3.

Antibody and EGF competition assay. A431 cells were treated with 10 nM biotinylated EGF in the presence or absence of 100 nM rat anti-EGFR antibody (2C2D3 or 4H7F4) or 100 nM cetuximab. After washing, cells were treated with Alexa 488-conjugated streptavidin, and stained cells were analyzed by flow cytometry. Mean fluorescence intensity (MFI) was calculated by subtracting the background MFI (no treatment with biotinylated EGF) from experimental MFI.