MiR-21 is one of the most overexpressed and well-studied miRNAs in both IBD56 and colorectal cancer.57 A recent meta-analysis has revealed a positive association between miR-21 expression in colon tissue and the development of IBD, suggesting miR-21 as a potential disease marker.56,58 In the context of murine colitis, we19 and others59 have shown increased miR-21 levels in IL-10–/– mice. The gene discussed is IL10; the disease is colorectal cancer.