Protease inhibition selectively increases anterior pressure in fibrosarcoma cells. (A) The majority of HT1080/MT1 cells migrating in 3D CDM adopt a polarized morphology with a clear leading and trailing edge of varying lengths (n = 45, N = 3). Bars, 10 µm. (B) Polarized HT1080/MT1 cells migrating in 3D CDM have low and uniform intracellular pressure (P_ic, measured in Pascals [Pa]) in control cells compared with the compartmentalized pressure in primary human fibroblasts (n = 18, N = 3). (C) Addition of a protease inhibitor (inh.) mixture (Wolf et al., 2003; see Materials and methods) triggers increased intracellular pressure anterior to the nucleus in HT1080/MT1 cells (n = 20, N = 3). (D) HT1080/MT1 cells migrating on 2D glass fail to respond to protease inhibition by raising or compartmentalizing their intracellular pressure (n = 20, N = 3; P = 0.7). Error bars indicate SEM. *, P < 0.01 versus the anterior compartment.