Urban and rural divergence in mortality trends: A comment on Case and Deaton.

pancreatic neuroendocrine tumor from a 12-week-old mouse, with tumor β-cells stained red and the surrounding exocrine tissue stained blue. Eliane Cortez et al. found that deleting the gene for platelet-derived growth factor DD (PDGF-DD) delayed tumor growth in a mouse model of pancreatic cancer, and that PDGF-DD stimulated proliferation of pancreatic β-tumor cells by binding to a subset of tumor cells expressing PDGF receptor β (PDGFRβ) and inducing secretion of additional growth factors. The results suggest that drugs targeting PDGFRβ may be useful in treating pancreatic neuroendocrine tumors. See the article by Cortez et al. on pages E864–E873. Image courtesy of Eliane Cortez, Michael Bartoschek, and Kristian Pietras (Lund University, Lund, Sweden). From the Cover