Displacement of beads by WT (gray) and R92Q (red) hiPSC-CMs contracting on a 10 kPa polyacrylamide gel. Videos were recorded at 30 frames/s using a spinning disc confocal microscope (Nikon). The cell, which is not visible, is on a rectangular pattern of Matrigel with a 7:1 aspect ratio. The displacement of the beads was tracked as a function of time. Note that the two cells shown are not on the same slide/hydrogel; rather, we have merged two videos to facilitate direct visual comparison of the contractility in WT and mutant cells. As is evident in the video, force is generated primarily along the long axis of the cells. These videos were used to generate the representative traces in Fig. S5.
