Cover picture: Distribution of traction stress exerted by a migrating NIH 3T3 fibroblast on the underlying substrate. Magnitude of traction stress was rendered as a color image, with iso-stress contours appearing as dark lines. Traction stress ranges from 9.20 × 10² dynes/cm² (violet) to 3.60 × 10⁵ dynes/cm² (red). Strong traction, shown in red, was constrained to a thin band along the leading edge of the cell. See the article by Munevar et al. on p. 1744.