In two patient populations, Gluten Containing Diet–Celiac Disease (GCD–CeD) and Gluten Free Diet–Celiac Disease (GFD–CeD), at the level of the duodenal biopsies, increased activity both of the EGFR/EGF (Epidermal Growth Factor Receptor/Epidermal Growth Factor) system and of the ERK (Extracellular Signal-Regulated Kinases) molecule has been demonstrated. The gene discussed is MAPK1; the disease is celiac disease.