Effects of inhibiting Rac1, ROCK, or myosin II on the migration of CHO-α4WT, CHO-α4Y991A, and CHO-α4S988A cells in microchannels. (A–C) CHO-α4WT (A), CHO-α4Y991A (B), and CHO-α4S988A (C) cells were treated with either the Rac1 inhibitor NSC23766, the ROCK inhibitor Y-27632, the myosin II inhibitor blebbistatin, or vehicle control and allowed to migrate inside VCAM-1–coated channels. Their migration velocities in channels of different widths were quantified. Data represent means ± SEM of >40 cells from three independent experiments. *, P < 0.005 relative to control. The images of migrating cells in designated channel widths and time points are also shown. White arrowheads show the centroid of cell body.