  The nucleon structure study in nuclear deep inelastic scattering is
considered. It is shown that nuclear data provide a new source of information
about dynamics of parton distributions in the nucleon. An example of the
neutron structure function extraction from the deuteron and proton data is
considered. The limit $x\to 1$ of the neutron to proton structure functions
ratio is studied. A link between the deep inelastic scattering off the nucleon
at high $x$ and elastic scattering off nuclei in high $Q^2$ region is
discussed.
