RBP4 and colorectal carcinoma: Among the 16 immune-related proteins, 6 proteins (MMP9, CYBB, RBP4, IGKV1-5, SERPIND1 and PGLYRP1) were only present in the stool of CRC patients, while the remaining 10 proteins (C3, A2M, ORM1, CAT, IGHG2, LTF, GPI, APOD, SERPINA3, and S100A6) were present at elevated levels in the stool of CRC patients (Supplementary Table 2).