Anti-VEGFR antibody specificity. Monoclonal antibodies MF-1 against mouse VEGFR-1, DC101 against mouse VEGFR-2, 6.12 against human VEGFR-1, and IMC-1C11 (abbreviated 1C11) against human VEGFR-2 specifically bind in dose-response fashion to (A) mouse VEGFR-1, (B) mouse VEGFR-2, (C) human VEGFR-1, and (D) human VEGFR-2, respectively. No antibody shows cross-reactivity with any other VEGFR or with the same receptor from the other species. These results indicate that each antibody has a strict binding specificity with its respective receptor. Error bars indicate standard error of mean absorbance.