  In this work, coherence effects in deep inelastic scattering (DIS) and in the
Drell-Yan (DY) process off nuclei are investigated, in particular nuclear
shadowing. The target rest frame and the color dipole formulation are employed.
Multiple scatterings are treated in Glauber-Gribov theory, which is modified to
include the nuclear form factor to all orders. Based on the mean coherence
length, which is defined in this work, it is estimated that gluon shadowing is
negligible at x_{Bj}>0.01. Parameter free calculations are compared to NMC and
E665 data for DIS and to E772 data for DY. In both cases, good agreement is
found. It is however not possible to reproduce the effect observed by HERMES.
For dileptons in proton-nucleus collisions at RHIC energies, considerable
shadowing for the whole x_F range is predicted. The influence of the nucleus on
the DY transverse momentum distribution is also studied. Furthermore, a new
parametrization of the dipole cross section is presented.
