Fragile epitopes-Antibody's guess is as good as yours.

Monoclonal antibodies recognize epitopes so specifically that altering a single residue can disrupt binding. In this issue of Science Signaling, Schüchner et al and Frohner et al report that flanking amino acids and an underappreciated posttranslational modification perturb epitope affinity for two groups of widely used monoclonal antibodies.