Myo9b is dispensable for T cell activation and expansion. (A) Exemplary synthetic WT (gray) and Myo9b^−/− (red) T cell tracks in a 1-mm diameter sphere containing 50 DCs (green). (B) Percentage of synthetic WT and Myo9b^−/− T cell contacts with at least one DC at high (10⁴) or low (50) DC densities. 100 synthetic T cell tracks were analyzed over an 8-h period. Shown is median with 25 and 75% quartiles and minimum/maximum values. (C) 2PM image of WT (gray) and Myo9b^−/− (red) OT-I T cells interacting with 100 nM OVA_257–264–pulsed DCs (green). HEVs are depicted blue. Square length, 8 µm. (D and E) Dynamic OT-I T cell–DC interaction parameters. Cell speeds (D) and interactions >30 min (E) of WT and Myo9b^−/− OT-I T cells with OVA_257–264–pulsed DCs. Pooled from four mice in two independent experiments. Horizontal bars in D depict mean and horizontal bars in E show median. (F–K) Activation and proliferation analysis of WT and Myo9b^−/− OT-I T cells. Percent CD69⁺ (F) and CD25⁺ (G) WT and Myo9b^−/− OT-I T cells at 24 and 48 h, respectively, after T cell transfer into mice containing 100 nM OVA_257–264–pulsed DCs. Shown is mean ± SD. Pooled from three independent experiments with 4–11 mice per condition. (H) Proliferation of e670-loaded WT and Myo9b^−/− OT-I T cells at 0 (gray shade), 48 (orange), and 72 h (red) after transfer. (I) Quantification of percent divided WT and Myo9b^−/− OT-I T cells at 48 and 72 h after transfer. Shown is mean ± SD. Pooled from three independent experiments with four to seven mice per condition. (J) Experimental layout of systemic LCMV-OVA infection. (K) Percentage of Myo9b^−/− OT-I T cells normalized to WT OT-I T cells at day 6 and 14 after infection (mean ± SEM). Pooled from three independent experiments with six to seven mice per time point. Statistical analysis: unpaired Student’s t test (D and K); Mann-Whitney test (E); ANOVA between selected columns with Sidak’s multiple comparison test (F, G, and I). *, P < 0.05; **, P < 0.01; ***, P < 0.001.