The present invention relates generally to a method for regulating cytokine signaling and agents useful for same. The method of the present invention is predicated in part on the identification of the molecular target of suppressor of cytokine signaling (SOCS) interaction in controlling cytokine signaling. The identification of the molecular target permits the development of assays to screen for a range of agonists and antagonists useful in modulating cytokine function. The present invention further provides, therefore, screening assays and more particularly high through-put screening assays for agonists and antagonists of SOCS-receptor interaction. Such agonists and antagonists are useful in the manufacture of medicaments for controlling cytokine signaling. Control of cytokine signaling is important for the treatment of a range of conditions including cancer, inflammatory conditions, immunological disorders and any other conditions involving aberrations of signal transduction.