FLT1 and neoplasm: Among the several non-protein VEGFR1 antagonists so far described [23, 25–27, 34, 35] those with proven in vivo tumor inhibition activity are a ribozyme, the DNAzyme DT-18, the hexapeptide GNQWFI and the 20-aminoacid peptide named BP-1 [23, 25–27].