Motility of different cancer cells in ring cell migration assay. (A) U87 cells, (B) U251N cells, (C) MDA-MB-231, (D) MCF-7, (E) HeLa cells. The gap areas photographed during ring cell migration assays from Figure 2 were measured using Image J software. The areas were plotted against migration time. For each plot, an equation and a R2 value were given. The slope (mm2/h) was used to indicate the difference in cancer cell motility. Values represent the mean ± s.e.m. (some of which are obscured by the symbols). N = 5 to 11 gaps from three rings. Data shown are representative of three independent experiments.