FGFR1 and cancer: Importantly, we show that 3xGFPp_FGF1E_LPET_MMAE displays veryhigh cytotoxicity against a panel of different cancer cells overproducingFGFR1 while remaining neutral toward cells devoid of FGFR1 expression.Our data implicate that the engineered fluorescent conjugates canbe used for imaging and targeted therapy of FGFR1-overproducing cancers.