Since heterozygous Men1+/– mice developed a spectrum of endocrine tumors similar to those observed in human patients with MEN1 syndrome (8, 23, 24), we tested whether hTS overexpression could also promote PanNET progression in heterozygote Men1-mutant (Men1+/ΔN3-8) mice. The gene discussed is APCDD1; the disease is multiple endocrine neoplasia type 1.