Cells to be used in producing antibody compositions, for example, an antibody having a high antibody-dependent cellular cytotoxic activity which is useful in various diseases, an antibody fragment or a fused protein having the Fc domain of the antibody; a process for producing an antibody composition by using these cells; antibody compositions; and uses thereof. In the above-described antibody compositions, the ratio of sugar chains, which are free from fucose bonded to N-acetylglucosamine at the sugar chain reducing end, to the total N-glycoside linkage complex sugar chains bonded to the Fc domain amounts to 20% or more. Moreover, novel GDP-mannose 4,6-dehydrogenase, GDP-keto-6-deoxymannose 3,5-epimerase 4-reductase, GDP-beta-L-fucose pyrophosphorylase, alpha-1,6-fucosyltransferase and DNAs encoding the same are provided.