Movie 1.

Spreading of control MEFs on stiff hydrogels. MEFs were cultured in DMEM-10% FBS to 70-80% confluency, trypsinized, and pre-incubated in suspension for 30 min in DMEM with 1 mg/ml BSA and vehicle (DMSO) as described in Materials and Methods. The cells were then plated on FN-coated stiff hydrogels in DMEM-10% FBS in the continued presence of DMSO. The cells were imaged every 15 sec for 15 min using the 40X objective of a Zeiss Axio Observer 7 inverted microscope. Scale bar = 30 μm. Movies were selected to show typical responses; n∼100 cells accrued from 2 independent experiments.