  High-precision electroweak production measurements from the Tevatron and the
LHC provide important constraints on the quark flavor separation in global PDF
fits. In this contribution, we study the impact of the recent D0 W asymmetry
measurements and of the LHCb W and Z Run I combination in the global NNPDF
analysis. We find that these measurements can be described by NLO QCD theory
and that they lead to a significant reduction of PDF uncertainties.
