FLT1 and neoplasm: The ability of r84 to bind human and mouse VEGF (Figure 1A, B) and block VEGF from binding and signaling through VEGFR2 (Figure 1C, Figure 2A–D, Figure S1A, B) makes r84 a unique tool for studying VEGF inhibition in tumor xenograft models, assessing possible toxicity induction and analyzing the importance of VEGFR1 signaling in these processes.