PDX1 and pancreatic insulinoma: A SSTR5 knockdown-induced increase of PDX-1 expression in mouse insulinoma MIN6 cells is accompanied by elevated expression of cyclin E and cdk4 and decreased expression of p21, p27, and p53, supporting previous studies showing that SSTR5 inhibits cell proliferation (Fagan et al., 1998; Feanny et al., 2008) and promotes apoptosis (Qiu et al., 2006).