The differential analysis identified the four proteins (COL12A1, THBS2, S100A8, and S100A9) showed significant up-regulation in the total 20 CRC patients, and the ROC analysis demonstrated the four proteins showed a well distinguish of CRCs from HCs with an AUC of 0.948 (Fig. 2H and Supplementary Fig. 2G). Here, S100A9 is linked to colorectal carcinoma.