  I present a determination of longitudinally-polarized parton distribution
functions of the proton from inclusive deep-inelastic scattering data:
NNPDFpol1.0+. This determination, based on the NNPDF methodology, upgrades a
previous analysis, NNPDFpol1.0, in two respects: first, it includes all new
data sets which have recently become available from the COMPASS experiment at
CERN and from the E93-009, EG1-DVCS and E06-014 experiments at JLAB; second, it
uses the state-of-the-art unpolarized parton set NNPDF3.0 as a baseline for the
reconstruction of fitted observables and for the determination of positivity
constraints. I discuss the impact of both these new inputs on the uncertainty
of parton distribution functions.
