SCAR is essential for efficient myosin-II-independent cytokinesis. Control (Ax3) and scar-null cells were grown in glass dishes in the presence of 40 μM blebbistatin. JK107 cells grown in the presence of 10 μg/ml doxycycline were transferred to medium lacking it (i.e. scar expression was repressed). (A) Every 24 hours cells were fixed, stained with DAPI and the number of nuclei per cell were counted. At least 100 cells were counted for each condition and the values plotted are the means ± standard deviation of three independent experiments. (B) Representative images of DAPI stained, fixed cells after 3 days growth in the conditions indicated. Scale bar: 50 μm. (C) JK107 cells were grown in medium lacking doxycycline for 24 hours and cytokinesis was imaged by DIC microscopy. Scale bar: 10 μm. Mitosis frequently resulted in a failed (bottom), or asymmetric (middle) division, with one daughter cell significantly larger than the other. (D) Frequency of symmetrical, asymmetric and failed cytokinesis in JK107 cells grown in either the presence or absence of 10 μg/ml doxycycline.