  We present the first Monte Carlo based global QCD analysis of spin-averaged
and spin-dependent parton distribution functions (PDFs) that includes nucleon
isovector matrix elements in coordinate space from lattice QCD. We investigate
the degree of universality of the extracted PDFs when the lattice and
experimental data are treated under the same conditions within the Bayesian
likelihood analysis. For the unpolarized sector, we find rather weak
constraints from the current lattice data on the phenomenological PDFs, and
difficulties in describing the lattice matrix elements at large spatial
distances. In contrast, for the polarized PDFs we find good agreement between
experiment and lattice data, with the latter providing significant constraints
on the spin-dependent isovector quark and antiquark distributions.
