Following gluteraldehyde quenching, ECM proteins were absorbed onto the PVA surface. Videos were recorded on a Axiovert 135TV (Carl Zeiss, Inc.) with a charge-coupled device camera (ORCA II ER; Hamamatsu Photonics). MetaMorph imaging software was used to acquire images and control all hardware. A custom environmental chamber (Lucite) enclosed both time-lapse and TIRF microscopes and maintained cells at 37°C with 10% CO2. Images were collected every 4 min and shown at 15 frames per second.