Actin-rich processes (light blue) in a transformed fibroblast protruding through extracellular matrix. The yellow spheres represent the centroids of beads added to the matrix to allow measurement of forces generated by the cell as it migrates through the 3D environment. The image shown is a wireframe representation of an isosurface rendering extracted from a time-resolved 3D series. (Image courtesy of Dr. James Evans of the Whitehead-MIT Bioimaging Center. Used with permission.)