MAP2K5 and malignant colon neoplasm: To address the functional role of MEK5/ERK5 signaling in colon cancer stem-like cells, HCT116, HT29, SW480, and SW620 cells were plated as tumorspheres, and grown in the presence of XMD8-92, a small-molecule inhibitor of ERK543 (Fig. 2a, b).