Lung cancer cells in the bronchus. In this issue (p 1351), Lewis Cantley and his colleagues show that a combination of PI3K inhibitors can treat certain types of mouse lung cancers. Image: Eye of Science/Photo Researchers

A small group of doctors are treating Lyme disease with long-term antibiotic therapies that mainstream researchers say are unproven and potentially dangerous. On page 1135, Coco Ballantyne reports on how this controversy has become increasingly polarized. The image shows a light micrograph of the tick that transmits Lyme disease. Cover photo: Alfred Pasieka/Photo Researchers, Inc.

This year’s election is one of the most momentous in recent US history. Our Editorial and a series of articles in our News section look at some of the key scientific issues of global importance that the next US president will have to tackle. Cover illustration: David Parkins (http://www.davidparkins.com)

Eosinophils use a catapult-like mechanism to ‘throw’ mitochondrial DNA at bacteria, report Hans-Uwe Simon and his colleagues in this issue (p 949). The cover shows an electron micrograph through an eosinophil. Credit: NIBSC/Photo Researchers, Inc.

In this issue, a News Feature by Cassandra Willyard takes a look at the various new approaches being developed in the lab and the clinic to mend sports injuries.

Cells from Zmpste24-/- progeroid mice and individuals with Hutchinson-Gilford progeria show nuclear abnormalities that are linked to aging-associated alterations. In this issue, Varela et al. (p 767) show that treatment with statins and aminobisphosphonates improves these aging-like phenotypes and extends lifespan in Zmpste24-null mice. The cover, courtesy of Carlos Lpez-Otn and his colleagues, shows a composition of teeth and cell nuclei from this animal model.

In this issue, Richard Flavell and his colleagues demonstrate that blocking TGF-β signaling in macrophages reduces plaque pathology in the brains of Alzheimer's disease model mice. The cover, courtesy of Terrence Town, shows macrophages in culture.

Studies of pancreatic islets in vitro lack a physiological environment, including vascularization and innervation. In this issue, Stephan Speier et al. have solved this problem by transplanting islets into the eye, which allows for in vivo noninvasive imaging under more natural conditions. The cover, courtesy of Per-Olof Berggren, shows an islet (red) engrafted on the vascular bed (green) of the iris.

Signaling by Slit ligands through Robo receptors is known to help guide neurite outgrowth. In this issue, Dean Li and colleagues describe a role for Slit-Robo signaling in the vasculature, where it inhibits angiogenesis and vascular leak. The cover image shows widespread Robo4 expression in the retinal vasculature of a 5-day-old mouse.

In this issue (p 331), Ru-Rong Ji and colleagues report that different matrix metalloproteinase family members play distinct roles in the initiation and maintenance of neuropathic pain. Image of a dorsal root ganglion courtesy of Ru-Rong Ji.

In this issue, Rita Perlingeiro and her colleagues show that embryonic stem cells can be induced with the transcription factor Pax3 to give rise to myocyte progenitors, which, as shown in the image, can engraft into injured mouse muscle. Image courtesy of Rita Perlingeiro.

In this issue (p 81), Christine Delprat and her colleagues report on the identification of a new, interleukin-17A-dependent mechanism of dendritic cell fusion in the rare disorder known as Langerhans cell histiocytosis. Image courtesy of Christine Delprat.