Cover legend: Confocal micrograph of a day 6 coculture of oligodendrocytes and dorsal root ganglion neurons, depicting a control and a mutant (Ilk−/−) oligodendrocyte. The control cell extends arbors that contact neighboring neuronal processes and produce membranous leaflets. In contrast, the Ilk-null oligodendrocyte is deficient in this ability. Green fluorescent protein (green) is expressed upon loss of Ilk, thereby labeling mutant cells. The sample was labeled with antibodies against neurofilament-200 (blue), myelin-basic protein (red), and stained with 4′,6-diamidino-2-phenylindole (white). For more information, see O'Meara et al. (pages 9781–9793).