A quantitative ELISA method was used to determinate the uPA, uPAR, and PAI-1 protein contents in peritoneal metastatic lesions and CEA-negative nonperitoneal metastatic tissues of 7 peritoneal metastasis patients, and CEA-negative normal peritoneal tissues of 24 nonperitoneal metastasis patients. The gene discussed is SERPINE1; the disease is metastasis.