PCNA and colonic neoplasm: Using PXR-humanized mice, rifaximin has been shown to significantly decrease the number of colon tumors induced by azoxymethane (AOM) and dextran sulfate sodium (DSS) treatment, increase survival rate, and inhibit NF-κB compared to wild type or PXR-null mice [36]. Proliferating cell nuclear antigen (PCNA) is a biomarker of colorectal cancer and its expression is associated with malignancy, angiogenesis, and metastasis [37,38].