Unsuspectedly, RBP-Jκ deletion in Ngn3 endocrine progenitors also resulted in focal areas of undifferentiated cells originating during pancreatic organogenesis, with evidence of chronic pancreatitis and metaplasia in the adult, illustrating that RBP-Jκ was also involved in the proper maturation and differentiation of the endocrine progenitors. This evidence concerns the gene RBPJ and chronic pancreatitis.