We previously reported that monomeric peptideselicit agonisticactivities only at very high concentrations and act practically asantagonists at physiologically attainable concentrations.8,34,40 In agreement with its high affinityfor EphA2, pre-treatment of the BxPC3 pancreatic cancer cells withtargefrin effectively antagonized EphA2 degradation induced by thepotent ephrinA1-Fc ligand, with an approximate EC50 ∼1.6 μM under these experimental conditions (Figure 4). Here, EPHA2 is linked to pancreatic neoplasm.