In pancreatic progenitor cells, HES1 expression inhibits the expression of Ptf1a, which controls exocrine cell differentiation, and Ngn3, which drives differentiation of endocrine cell types that will form the islets of Langerhans.
Pdx1+ pancreatic progenitor cells also co-express Hlxb9, Hnf6, Ptf1a and Nkx6-1, and these progenitor cells form the initial pancreatic buds, which further proliferate and branch in response to FGF-10 signaling.