A novel examination method for accurately evaluating the effectiveness of treatment with an anticancer drug for the administration of the anticancer drug targeting a tumor-associated factor receptor is provided. In order to evaluate the effectiveness of trastuzumab (Herceptin.TM.) of an anticancer drug, it was found to be meaningful to examine the expression of MUC4, that is, a substance which interacts with HER2/c-erbB-2 belonging to the epidermal growth factor receptor family on the surface of and/or within the cell membrane. From this fact, in order to treat various cancers with an anticancer drug targeting the tumor-associated factor receptors, it was found to be meaningful to detect previously the expression of intracellular ligands against the receptors. The finding completes the present invention.