On the cover: Differential ability of double-positive (DP) and single-positive (SP) thymocytes to spread and adhere. CD4-SP (green) and CD8-SP (red) thymocytes spread, adhere, and polarize their microtubule organizing center (MTOC) efficiently on anti-CD3⁺ anti-CD28 coated surfaces, whereas, DP thymocytes (yellow) form small contacts and do not polarize their MTOCs. Hailman E., and P. M. Allen. 2005. Inefficient cell spreading and cytoskeletal polarization by CD4⁺CD8⁺ thymocytes: regulation by the thymic environment. J. Immunol. 175: 4847–4857.