  We explain the current status of nuclear parton distribution functions in
connection with neutrino-nucleus interactions. Neutrino deep inelastic
scattering (DIS) measurements have been done for heavy nuclear targets such as
iron and lead. In order to extract structure functions of the nucleon, one
needs to remove nuclear effects from the data. However, recent studies indicate
that there are inconsistencies in nuclear modifications between charged-lepton
and neutrino scattering measurements. Nuclear medium effects could be also an
origin for the NuTeV anomaly in the weak-mixing angle. In addition, the
modifications could affect neutrino-oscillation experiments because some DIS
events of neutrino-oxygen nucleus interactions are contained. On the other
hand, the nuclear medium effects themselves are interesting and important for
describing nuclei in terms of quark and gluon degrees of freedom.
