Despite a lack of evidence, the importance of macrophage polarization to tumor initiation is supported by studies that used Il10−/− mice colonized with E. faecalis or E. coli, transgenic mice overexpressing the transcription inhibitor Zeb2 or the ApcMin/+ mouse model, as well as the treatment of mice with AOM and dextran sulfate sodium (DSS; Box 1) to induce colitis and tumor formation. Here, IL10 is linked to colitis.