ART4 and digestive system neoplasm: Clinically, the common tumour markers of malignant gastrointestinal tumours mainly include embryonic antigens (e.g., AFP and CEA), glycoprotein antigens (e.g., CA-199, CA-125, CA15-3, CA72-4, CA-242, and CA-50) and protein antigens (CyFRA21-1 and Her 2).