Disclosed herein are methods of increasing epithelial cell proliferation (such as intestinal epithelial cell proliferation) by contacting epithelial cells with one or more CBPs. In some examples, the methods include administering the CBP to a subject, such as a subject in need of increased epithelial cell proliferation. Also disclosed herein are methods of identifying a subject having or at risk of developing hyperproliferation of epithelial cells (such as intestinal epithelial cells). Further disclosed are methods of decreasing epithelial cell proliferation by decreasing expression and/or activity of a CBP and methods of identifying inhibitors of epithelial cell proliferation and/or CBP activity.