  We extract the Boer-Mulders functions of valence and sea quarks in the proton
from unpolarized $p+D$ Drell-Yan data measured by the FNAL E866 Collaboration.
Using these Boer-Mulders functions, we calculate the $\cos 2 \phi$ asymmetries
in unpolarized $pp$ Drell-Yan processes, both for the FNAL E866/NuSea and the
BNL Relativistic Heavy Ion Collider (RHIC) experiments. We also estimate the
$\cos 2 \phi$ asymmetries in the unpolarized $p\bar{p}$ Drell-Yan processes at
GSI.
