CERS5 and colonic neoplasm: However, on the basis of (1) immunohistochemical staining of tight junctions proteins ZO-1 and occludin in CerS5-ko and CerS5-wt colon tissue, and (2) barrier functional tests, showing no impairment but rather an enhanced barrier function in CerS5-downregulated colon cancer cells, and 3) due to the fact that CerS5fl/fl VilCre mice showed no higher sensitivity towards AOM/DSS treatment, it seems unlikely that CerS5 has an impact on the colon barrier.