FGF1 and cancer: Importantly, its cytotoxicity is one of the highest (EC50 in the subnanomolar range) among the conjugates targetingFGFR1 described to date.25,26,28,53 For comparison, monomeric conjugatescomposed of FGF1 and MMAE display much higher EC50 values(50–150 nM, depending on the cell line).25,52 These data suggest that the oligomerization of the targeting moleculeswith GFPp scaffolds not only improves the selective delivery of cytotoxicdrugs to cancer cells but also allows for monitoring the distributionand intracellular trafficking of the conjugate.