Thus, our structural analyses of GIF:GM-CSF and GIF:IL-2 complexes by several orthogonal approaches including X-ray crystallography, EM, SAXS and SEC-MALLS illustrate that the two GIF–cytokine complexes are structurally distinct based on the ability of dimeric GIF to sequester two copies of each cytokine to yield stable assemblies obeying 2:2 stoichiometry.