Gefitinib treatment worked for the suppression of tumor growth, whereas intestinal apoptosis was significantly frequent in the mice treated with a high dose of gefitinib (100 mg/kg b.w.), and also the treated mice exhibited an increasing trend in the level of plasma alkaline phosphatase, GOT, GPT and (total-, direct- and indirect-) bilirubin. This evidence concerns the gene GPT and neoplasm.