S100A9 and colorectal carcinoma: We performed immunohistochemical (IHC) staining to detect the expression of S100A8 and S100A9 in sections of 42 pairs of samples (CRC and matching distal normal tissues) and found that S100A8 and S100A9 were elevated in tumor cells of CRC tissues compared with the matching distal normal tissues (Fig. 1A and B).