IL4 and colorectal cancer: However, the concentrations of M2 polarization-related factors IL-1β and IL-4 also increased in the peripheral blood of patients with stage IV colorectal cancer (one-way ANOVA, IL-1β stage II vs stage IV, p = 0.0371; IL-4 control vs stage IV, p = 0.0122), suggesting the presence of M2 macrophage-mediated pro-tumor function in patients with stage VI colorectal cancer (Figure 2B).