The ErbB receptor tyrosine kinases – epidermal growth factor receptor (EGFR), ErbB2, ErbB3, and ErbB4 – are important for homeostatic maintenance of the intestinal tract, and defects in ErbB signaling can contribute to the pathophysiology of IBD.11, 12, 13 However, study of these receptors in the GI tract has traditionally focused on their role in epithelial biology, including cell proliferation, survival, and migration. This evidence concerns the gene ERBB4 and inflammatory bowel disease.