  We calculate and resum a perturbative expansion of nuclear enhanced power
corrections to the structure functions measured in deeply inelastic scattering
of leptons on a nuclear target. Our results for the Bjorken $x$-, $Q^2$- and
$A$-dependence of nuclear shadowing in $F_2^A(x,Q^2)$ and the nuclear
modifications to $F_L^A(x,Q^2)$, obtained in terms of the QCD factorization
approach, are consistent with the existing data. We demonstrate that the
low-$Q^2$ behavior of these data and the measured large longitudinal structure
function point to a critical role for the power corrections when compared to
other theoretical approaches.
