Fig. 3.

Effect of α5β1 integrin expression on cell invasion in 3D ECMs. (A) α5 integrin subunit expression of parental MDA-MB-231 cells. (B) α5 and (D) β1 integrin subunit expression of α5β1^low and α5β1^high cells. In each histogram, left curves are isotype controls and filled gray curves show integrin expression. One representative experiment out of five is shown. The corresponding bar graphs show MFI values (mean + s.e.m., n=5). (C) A higher percentage of α5β1^high cells invaded into 3D ECMs compared to α5β1^low cells after 3 days. (E) Invasion profiles show that α5β1^high cells migrated deeper into 3D collagen matrices than did α5β1^low cells. (F) Aspect ratio of invaded α5β1^high and α5β1^low cells after 3 days. Bright field images of α5β1^high (lower image, depth 180 μm) and α5β1^low cells (upper image, depth 68 μm) inside collagen gels. (G) The MSD of α5β1^high cells was significantly greater than that of α5β1^low cells. Inset: invasion speed of α5β1^high and α5β1^low cells in 3D ECMs. Calculated slopes for the power-law exponent β=1 and β=2 are shown. (H) The apparent diffusivity was increased in α5β1^high cells, indicating a higher migration speed. (I) The 3D motility of α5β1^high cells was more persistent than that of α5β1^low cells, as shown by a higher β. *P<0.05, **P<0.01, ***P<0.001.