FGFR1 and cancer: We have recentlyshown that FGFR1 clustering either with engineered multivalent antibodiesor oligomeric ligands strongly enhances the efficiency and altersthe mechanism of receptor endocytosis.24,30,31 We have also demonstrated that high affinity of FGFR1-specificantibodies promotes their uptake via receptor-mediated endocytosis.24,29,31 These results implied that theoligomeric cytotoxic conjugate 3xGFPp_FGF1E_LPET_MMAE, due to itsvery high affinity for the receptor and FGFR1 cross-linking potential,could serve as a highly efficient drug carrier for the treatment ofFGFR1-overproducing cancers.