Figure 2.

Tracking migration of cancer cells undergoing durotaxis in response to a stiffness gradient. (A) U87 glioblastoma cells seeded on a polyacrylamide stiffness gradient to which fibronectin had been covalently coupled. Dashed lines indicate the 250-μm-wide soft, medium, and stiff regions; phase-contrast microscopy. (B) Representative tracks of U87 glioblastoma cells migrating on a stiffness gradient, with greater stiffness toward the top. Black tracks indicate cells with net translocation toward the stiffer end of the gradient after 8 h (10 of 16 cells in this example). Red tracks indicate cells with net translocation against the gradient. (C) Representative tracks of U87 cells migrating on the soft (2–7 kPa) region of a stiffness gradient. Note that a higher proportion of cells on this soft region of the gradient migrate toward the stiffer end of the gradient substrate (black tracks; 10 of 14 cells) compared to cells migrating opposite to the gradient (red). To see this figure in color, go online.