Description and validation of a new method for detecting EGFR expression using biotinylated cetuximab.

<p>(A) Biotinylated cetuximab is used as a primary antibody to detect EGFR, and an avidin-FITC secondary antibody is used during FCM to detect antigen–antibody complexes. (B: biotin, A: avidin) (B) FCM analysis of EGFR expression by A431 cells. Controls with antihuman, nonspecific IgG1 antibody labeled with FITC are described in red and cetuximab-biotylated antibody in blue. Fluorescence intensity is approximately 5-times higher relative to the control antibody.