2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/190901Recent data on polarized proton knockout reactions off He-4 nuclei suggest a small but nonzero modification of proton electromagnetic form factors in medium. Using model independent relations derived on the basis of quark-hadron duality, we relate the medium modification of the form factors to the modification at large x of the deep-inelastic structure function of a bound proton. This places strong constraints on models of the nuclear EMC effect which assume a large deformation of the intrinsic structure of the nucleon in medium.16 pages, 3 figures; typos corrected, references added, fig. 2 labels corrected; version to appear in Eur. Phys. J. ANuclear TheoryHigh Energy Physics - PhenomenologyNuclear Experimenttext