  The reweighting method presented in earlier publications is applied for
incorporating the LHC W lepton asymmetry data published in 2010 into the
NNPDF2.1 NNLO analysis. We confirm the result of the NLO analysis which
indicated that these data reduce PDF uncertainties of light quarks in the
medium and small-x region, providing the first solid constraints on PDFs from
LHC data.
