Evaluation of [18F]TFPFN-2Rs15d conjugate: A) SDS-PAGE; left lane molecular weight markers, right lane [18F]TFPFN-2Rs15d. B) Size-exclusion HPLC; 18F-activity profile in blue; UV HPLC profile of protein molecular weight (red dashed line) — 1 thyroglobulin (670 kDa), 2 γ-globulin (158 kDa), 3 ovalbumin (44 kDa), 4 myoglobin (17 kDa), 5 vitamin B12 (1.4 kDa). C) Double reciprocal plot from the Lindmo immunoreactivity assay. D) Binding affinity determined on BT474M1 cells.