Hydroxylated collagen peptide (AGP) and two additional NOPs derived from collagen alpha-1(I) and collagen alpha-1(III), which were measured by multiple reaction monitoring and parallel reaction monitoring (PRM) approaches, respectively, were found to complement serum CEA to improve the detection of CRC liver metastases (15–20% increase in sensitivity)13,14. The gene discussed is CEACAM5; the disease is colorectal carcinoma.