In this issue (p 1797), Val Sheffield and his colleagues identify a role for neural progenitor cells in the development of neonatal hydrocephalus. The cover shows ependymal motile cilia lining the cerebral ventricles. Image courtesy of Thomas Moninger and Calvin Carter (University of Iowa).

In this issue, Andrew Weng and his colleagues uncover a new mechanism by which oncogenes regulate leukemia stem cells. Notch-driven inactivation of PKCθ attenuates the accumulation of reactive oxygen species to lower oxidative stress in the stem cell population of T cell acute lymphoblastic leukemia (ALL), contributing to tumorigenesis. The image shows an electron micrograph of erythrocytes and lymphocytes from a patient with ALL. Photo by Steve Gschmeissner/Science Photo Library.

In this issue, Kusminski et al. identify a way to expand white adipose tissue in a metabolically healthy manner through manipulation of mitochondrial activity. Adipose tissue expansion in the most obese mouse recorded to date unexpectedly preserves normal insulin sensitivity, even during extreme metabolic challenges. Cover image credit: David Gresham, Christine Kusminski, William Holland and Jiyoung Park. Cover designL Matt Hansen

Antiretroviral therapy has transformed outcomes for HIV-1–infected individuals. In this issue, Rosenbloom et al. (p 1378) model the dynamics of different antiretroviral drugs, shedding new light on the distinct patterns of viral resistance observed clinically. The editorial also reflects on the future of HIV therapy with the current push toward achieving a cure. Cover image credit: Karen Vanderbilt

In this issue, Yoshiaki Kubota and his colleagues (p 1208) discover that impaired oxidative defense—due to loss of the ATM protein kinase—blocks pathological angiogenesis in the retina and in tumors. The cover shows wholemount staining of a retina from an Atm-deficient mouse in a model of ischemic retinopathy, illustrating that these mice are protected from neovascular tuft formation. Green, isolectin B4 (blood vessels); red, a-smooth muscle actin; blue, DAPI.

Tissue fibrosis is a costly unmet medical need. In this issue (p. 1028), Wynn and Ramalingam review our current understanding of the mechanistic basis of fibrosis, pointing to future directions for the discovery of new therapies. The cover shows a colored computed tomography scan through the chest of a patient with pulmonary fibrosis, showing the lung tissue in green and the fibrotic areas in orange. Image: Du Cane Medical Imaging LTD/Science Photo Library.

In this issue, Tenbaum et al. (p 892) uncover a malignant crosstalk between activated β-catenin and FOXO signaling that promotes metastasis of colon tumors, a potential negative outcome of targeted therapy. The cover shows a confocal microscopy image of a double immunofluorescence staining for β-catenin (red), FOXO3a (green) and Hoechst (blue) in a paraffin section of a human colon adenoma. Image courtesy of Irene Chicote and Héctor G. Palmer, Stem Cells and Cancer Laboratory, Vall d'Hebron Institute of Oncology, Barcelona, Spain.

This month we feature a collection of reviews on asthma. The cover shows a pseudocolor electron micrograph of a mouse lung. Image courtesy of Thomas Deerinck and Mark Ellisman, NCMIR, University of California–San Diego.

In this issue (p 572), Stuart Forbes and his colleagues describe how, during injury, damage-specific signaling from myofibroblasts (green) and macrophages (blue) regulates the fate of hepatic progenitor cells (red) in the regenerative niche. The cover shows a three-dimensional reconstruction of a regenerating liver. Collagen, yellow. Image courtesy of Sang Soo Seo, Luke Boulter and Stuart Forbes (University of Edinburgh).

In this issue (p 413), Jonathan Tilly and his colleagues report the isolation of oogonial stem cells from mouse and adult human ovaries, and show that the human cells can generate oocytes in vitro and within human ovarian xenografts in vivo. The cover depicts mouse oogonial stem cell–derived oocytes that have been fertilized in vitro to produce embryos. Image courtesy of Yvonne White, Dori Woods and Jonathan Tilly (Massachusetts General Hospital and Harvard Medical School).

In this issue (p 227), Ying Zhang and colleagues identify a role for Smurf2 in suppressing tumorigenesis. Smurf2 regulates chromatin structure and genome stability through a newly identified target, RNF20. The cover shows the co-localization of Smurf2 with DNA damage markers in the nuclei of human osteosarcoma cells. Image courtesy of Ying Zhang (National Cancer Institute, NIH).

Improved methods for imaging the spinal cord after injury in experimental animals could facilitate the development of new therapies. In this issue (p. 166), Frank Bradke and his colleagues use a tissue-clearing procedure to achieve three-dimensional imaging of neurons and glia in the regenerating spinal cord. The cover shows a reconstruction of GFP-labeled neurons in the spinal cord of an uninjured mouse. Image courtesy of A. Erturk and F. Bradke.