Myo9b facilitates T cell transmigration through increasingly tight ECM barriers. (A) Scanning electron micrographs of uncoated, laminin, LD, and HD collagen–coated Transwell filters with 5-µm pore size. Bars: 20 µm (top row); 5 µm (bottom row). (B) Chemotactic migration as percent of input of WT and Myo9b^−/− T cells in uncoated and coated Transwell filters. Pooled from three independent experiments. Horizontal bars depict mean. (C) Normalized ratio of WT and Myo9b^−/− T cell migration through uncoated and coated Transwell filters. Shown is mean ± SEM. (D) Chemotactic migration as percentage of input through HD collagen–coated Transwell filters in presence of indicated inhibitors. Pooled from three independent experiments. Shown is mean ± SEM. Statistical analysis: unpaired Student’s t test (B); ANOVA against “uncoated” and “untreated”, respectively, with Dunnett’s multiple comparison test (C and D). *, P < 0.05; **, P < 0.01; ***, P < 0.001.