USC cell lines are significantly more sensitive to epothilones when compared to paclitaxel. Representative dose-response curves and IC50 values as determined by flow cytometry after exposure to patupilone, ixabepilone and paclitaxel for 72 hours in USC-1 cell line are shown. IC50 values (mean) for patupilone, ixabepilone and paclitaxel are 0.41, 0.87 and 2.14 nM, respectively (paclitaxel vs patupilone: p = 0.003, paclitaxel vs ixabepilone: p = 0.02; patupilone vs ixabepilone: p = 0.02).