Amoeboid-like motility observed after vincristine treatment. A. Cellular morphology after 24 h drug treatment. Cells (2.5 × 105) were seeded into wells of 6-well plates and incubated for 24 h on gelatin-coated coverslips with or without vincristine or paclitaxel. F-actin was labeled with Alexa Fluor 488 phalloidin, and nuclei were labeled with DAPI. F-actin (green) and nuclei (blue) were analyzed using confocal microscopy. Arrows indicate cell protrusions. Arrowheads indicate membrane blebs. White bars, 10 μm. B. Detection of blebbing cells and apoptosis. Cells on gelatin-coated coverslips were treated with vehicle or drugs, fixed and stained with TRITC phalloidin, cleaved caspase-3 antibody and DAPI. F-actin (red), cleaved caspase-3 (green) and DAPI (blue) were analyzed using confocal microscopy. Arrows indicate the cells with membrane blebs. White bars, 10 μm. C. DIC images from supplemental videos of the control cell (Additional file 1: Video S1) and the 15 μM vincristine-treated cell (Additional file 2: Video S2). Cells (6.25 × 103) were confined to a 50% Matrigel environment with or without 15 μM vincristine on a 35 mm glass-bottom dish by a coverslip. Frames show the cells at the indicated times. Arrows indicate cell protrusions. Arrowheads indicate membrane blebs.