It is shown that the relative sign between the NNω and πρω
coupling constants can be determined most sensitively from ω production
processes in NN collisions. Recent data on these reactions clearly favor the
sign of the πρω coupling constant which is opposite to that
inferred from studies of the photoproduction reaction in combination with the
vector meson dominance assumption and used by many authors. Implication of this
finding in the description of other reactions is discussed.Comment: 6 pages, 4 figures, REVTeX, to be published in Phys. Lett.