Figure 1. Conformation-sensitivity of the epitope recognized by nimotuzumab. Coating extracellular region EGFR recombinant protein was sequentially treated with DTT and iodoacetamide to disrupt disulfide bonds. Binding of nimotuzumab to either treated or non-treated antigen was detected with anti-human IgG antibodies labeled with horseradish peroxidase. Relative antigenicity (%) of denatured erEGFR was calculated taking the reactivity toward the unmodified antigen as the reference. Cetuximab and polyclonal anti-erEGFR monkey antiserum were used as control antibodies.