<;P>;PROBLEM TO BE SOLVED: To provide a new anticancer agent containing an SOCS activation agent as an active component and provide a method for screening the anticancer agent. <;P>;SOLUTION: The anticancer agent contains the SOCS (Suppressor Of Cytokine Signaling) activation agent as the active component. Proliferation of cancer cells is effectively suppressed to enable treatment of cancers by using the SOCS activation agent containing a substance to suppress a pathway through Jak1 but independent on STAT3 as the active component. Especially, the substance of the anticancer agent to suppress the pathway through Jak1 but independent on STAT3 is an SOCS-3 gene. <;P>;COPYRIGHT: (C)2010,JPO&INPIT