Interestingly, hyperactivation of MAPK signaling (via TGF-α mediated activation of EGFR) is observed in Menetrier’s disease, a hypertrophic gastropathy characterized by hyperproliferation of isthmus progenitors and the preferential differentiation of these progenitors into surface mucous cells at the expense of parietal and chief cells (Fiske et al., 2009). Here, TGFA is linked to gastric mucosal hypertrophy.