  Effect of bound nucleon internal structure change on nuclear structure
functions is investigated based on local quark-hadron duality. The bound
nucleon structure functions calculated for charged-lepton and (anti)neutrino
scattering are all enhanced in symmetric nuclear matter at large Bjorken-$x$
($x \agt 0.85$) relative to those in a free nucleon. This implies that a part
of the enhancement observed in the nuclear structure function $F_2$ (in the
resonance region) at large Bjorken-$x$ (the EMC effect) is due to the effect of
the bound nucleon internal structure change. However, the $x$ dependence for
the charged-lepton and (anti)neutrino scattering is different. The former
[latter] is enhanced [quenched] in the region $0.8 \alt x \alt 0.9$ [$0.7 \alt
x \alt 0.85$] due to the difference of the contribution from axial vector form
factor. Because of these differences charge symmetry breaking in parton
distributions will be enhanced in nuclei.
