H&E staining showed that adenoma formation was accompanied by diffuse immune cells infiltration in the colons of WT, C3-deficient, and C5ar2-deficient mice, while more mucosa-associated lymphoid tissues suspected as tumors (as shown in Figure 1E) were observed in C5- and C5ar1-deficient mouse colons (Figure 1G, upper panel). Here, C5AR1 is linked to adenoma.