Figure 4. Stiffness-mediated differentiation phenotype induces upregulation of podocyte-specific functional proteins.

(A) Representative images of Western blots for five proteins critical for physiological function of podocytes. Images of the complete blots are shown in Figure S3. (B) Quantification of kidney podocyte protein markers. Highest upregulation of WT-1 was found on the 2 kPa gel (2.2 ± 0.3). Nephrin, podocin, and CD2AP showed similar trends. Synaptopodin did not show this trend and there was no statistical difference between softer gels and control. T-statistics showed statistically significant changes of the ratios of five protein markers after normalization by control (two-tails, α = 0.05). The average t-statistics were 4.5 for the 2 kPa gel and 4.0 for the 5 kPa gel, which were significantly different relative to the control. Those for the 0.6 kPa and 13 kPa gels were 0.8 and 1.5, and the differences were not significant.