File Name : figure s1.pdf Caption : figure s1. distribution of h9c2 cells. h9c2 cells were evenly distributed across the substrate surface. a) the representative distribution of h9c2 cells across the substrate was constructed from 27 adjacent images taken across a 9x4mm2 section of the hydrogel. the average position of cells on the x and y axis is indicated by the yellow cross. b) based on the dapi stain, the cell density at each stiffness was calculated. across all stiffnesses and ecm, no significant differences in cell density were detected (two-way anova, p>0.05, n=7), however on collagen coated hydrogels, cells tended to be more densely packed between 12 and 22kpa. File Name : figure s2.pdf Caption : figure s2. relationship between mechanomarker localisation and cell morphology. mrtf-a and yap localization was compared to nuclear area and cell area. a) no discernable trends were observed between nuclear area and mrtf-a localization, but a weak correlation can be detected between nuclear-mrtf-a localization and increasing nuclear area in fn and ln coated hydrogels, but not col coated hydrogels (pearson’s correlation, col-r2=0.002, p>0.05, n= 4; fn- r2=0.01, p<0.05, n=4; ln- r2=0.14, p<0.05, n=4). b) conversely, a weak negative relationship can be observed between the nuclear localization of mrtf-a and cell area (pearson’s correlation, col-r2=0.002, p>0.05, n= 4; fn- r2=0.01, p<0.05, n=4; ln- r2=0.14, p<0.05, n=4). the same trends can be seen between yap and c) nuclear size (pearson’s correlation, col-r2=0.03, p<0.05, n= 4; fn- r2=0.04, p<0.05, n=4; ln- r2=0.08, p<0.05, n=4) and d) cell size (pearson’s correlation, col-r2=0.10, p<0.05, n= 3; fn- r2=0.13, p<0.05, n=3; ln- r2=0.17, p<0.05, n=4), whereby yap becomes increasingly nuclear localized with increasing nucleus size and decreasing cell size.