Impact of PDF uncertainties on extra-dimensions sensitivity at LHC

The LHC data will provide sensitivity to an unification of the couplings at low energies in the range $\sim$10-100 TeV. It is demonstrated in this note that the lack of knowledge on the proton structure, specifically its gluon distribution, can lower dramatically the sensitivity of bare cross section measurements to this physics. However, some more elaborated strategies could probably be developped to recover an important part of the sensitivity