A schematic diagram showing the effects of Shh signaling during intestinal remodeling. Shh appears to enhance the proliferation of cells in all three tissue layers during metamorphosis. Shh receptors and downstream transcription factors are highly expressed in the connective tissue, which are likely responsible for the activation of the expression of BMP-4, Snai2, and Twist1. The connective tissue may in turn help to mediate the cell proliferation effects of Shh on the adult epithelial stem cells and the circular muscle cells. Cyclopamine directly inhibits Shh signaling in the epithelium and thus blocks all the effects of Shh.