  We argue that nuclei are not transparent for fast projectile partons. Color
transparency is effective for final state interactions in heavy particle
production, though nuclear filtering of initial partons can reduce the cross
sections. We show that short-ranged initial state interactions, which have been
neglected so far, can be important in hadroproduction on nuclei. With the
present scenario of hadroproduction a qualitative description of data can be
obtained.
