Figure 4. Naïve macrophage response to anti-inflammatory M2 signaling cues is attenuated when cells are cultured on stiff culture substrates. (A) Final urea concentrations in cell lysate following arginase activity assay for naïve macrophages cultured on differentially stiffened substrates (n=8-12). (B) Urea concentrations in cell lysates following arginase activity assay as a function of substrate stiffness and cECM coating age (n=4). (C) Representative immunolabeling of Arginase-1 (ARG) and cell nuclei (DAPI) in Th2 cytokine treated macrophages cultured on 8 kPA gels, 64 kPA gels, or tissue culture plastic each coated with either young or aged cECM. Image contrast adjusted to reduce background fluorescence. Scale bars = 100um. Data reported represents mean values with boxes representing 25%/75% of mean. Error bars represent standard deviation. ANOVA with Tukey HSD post-hoc analysis. * p<0.05, ** p<0.001.