GSK3β is a constitutively active serine/threonine kinase featured in two signaling pathways that are of particular importance for intestinal epithelial cell proliferation and colorectal cancer: the Wnt/β-catenin pathway and the phosphatidylinositol 3-kinase (PI3K)/Akt pathway [16,20,21]. Here, MARK2 is linked to colorectal cancer.