This image shows an embryonic mouse dorsal root ganglion (DRG) explant subjected to nerve growth factor (NGF) deprivation and stained with the calcium indicator Fluo-4. NGF deprivation induces a large increase of intracellular calcium in NGF-dependent DRG sensory neurons, but this is significantly reduced in neurons lacking the amyloid-precursor protein. Dark blue colors represent baseline (low) levels of calcium and warmer colors (green-yellow) indicate an increase in intracellular calcium. For more information, see the article by de León et al. (pages 6680–6691). Cover image: Andres de León.