TCF7L2 and type 2 diabetes mellitus: Most α-cellsdid not exhibit Wnt pathway activation and instead expressed high levels of thenoncanonical Wnt, Wnt4, which can act to repress canonical Wnt signaling [15].The upregulation of TCF factors, including TCF7L2, is particularly interestingas linkage studies have identified a polymorphism in that gene as being tightlylinked to type II diabetes in humans and there is some evidence that thispolymorphism affects β-cellfunction [16–20].