S100A9 and colorectal carcinoma: Another study suggests that CCL5-deficient transgenic mice may delay tumor growth and metastasis by inducing reduced expression of S100a9 (S100 calcium-binding protein A9) in CD11bhiF4/80low tumor-associated macrophages, further promoting the accumulation of CD8+ T cells to tumor sites in a CRC mouse model (35)(Figure 1).