On the cover: Single-cell Ca²⁺ live imaging in classified T cells. Color-coded details of an ongoing Ca²⁺ imaging experiment at a single measurement point. Warmer colors (yellow/red) indicate high Ca²⁺ influx while colder colors (blue/pink) indicate low Ca²⁺ influx in TCR-triggered CD4⁺ T cells. Schwarz, A., M. Schumacher, D. Pfaff, K. Schumacher, S. Jarius, B. Balint, H. Wiendl, J. Haas, and B. Wildemann. 2013. Fine-tuning of regulatory T cell function: the role of calcium signals and naive regulatory T cells for regulatory T cell deficiency in multiple sclerosis. J. Immunol. 190: 4965–4970.