Morgan et al. BMC Cancer 2010, 10:89 http://www.biomedcentral.com/1471-2407/10/89 Page 5 of 9 Figure 3 (a) HXR9 toxicity was determined using the MTS assay. SK-OV3 and OV-90 cells were treated overnight with 30, 60, 90 and 120 μM of either CXR9 or HXR9. A sample of the same cell suspension was used as a “cell-only” control. Results here are presented as an average of three independent experiments ± SEM. The IC50 for SK-OV3 was estimated from the graph to be 70 μM, no value could be determined for OV-90. (b) Phase contrast micrographs of SKOV-3 cells treated overnight with 60 μM of HXR9 or CXR9. In HXR9 treated cultures, fewer number of adherent cells were evident and many detached, dead cells were apparent. (×120 magnification) Figure 4 Fluorescence activated cell sorter (FACS) analysis of Annexin V-PE stained SK-OV3 cells. Induction of apoptosis in SK-OV3 cells treated overnight with HXR9 or CXR9 (120 μM) was compared with untreated cells. The results are presented as mean values ± SEM of five independent experiments. ** indicates a significant difference between treatment groups, p < 0.001.