CEA (carcinoembryonic antigen) is an acidic glycoprotein with the characteristics of human embryo antigen. It exists on the surface of cancer cells derived from endodermal cells and is a structural protein of cell membrane. This protein is formed in the cytoplasm and secreted into the surrounding body fluids. Therefore, it can be detected in various body fluids and excreta such as serum, cerebrospinal fluid, breast milk, gastric juice, pleural and abdominal fluid, urine and feces. As a specific marker for the early diagnosis of colon and rectal cancer, CEA level is found to increase not only in gastrointestinal malignancies, but also in serum of breast cancer, lung cancer and other malignancies through a large number of clinical practices.Therefore, CEA is a broad-spectrum tumor marker. Although it cannot be used as a specific index for the diagnosis of certain malignant tumors, it still has important clinical value in the differential diagnosis, disease monitoring and efficacy evaluation of malignant tumors.This product is the recombinant human CEA protein expressed from human 293 cells (HEK293).