  Distortions of bound nucleon space-time structure, measured in deep inelastic
scattering off nuclei, are discussed from view-point of a theoretical approach
based on the Bethe-Salpeter formalism. It is shown that modification of the
structure function $F_2^{\rm N}$ results from relative time dependence in Green
functions of bound nucleons. The modification plays fundamental role in
analysis of deep inelastic scattering experiments and allows one to obtain new
information about nucleon structure.
