Non-cytotoxic concentration of patupilone counteracts IR-enhanced MMP activity. A , MMP activity was determined in the CM derived from HT1080 cells treated with 0.2 nM patupilone and indicated doses of IR. Cells were pretreated with or without patupilone for 24 h and sham-treated or irradiated with the indicated doses of IR. The cell culture media was discarded 1 h after irradiation and cells were incubated for additional 24 h in serum-free medium to obtain CM, n = 13. B , clonogenic cell survival of HT1080 cells was determined after treatment with increasing doses of patupilone and IR, n = 3. *P < 0.05, **P < 0.01, ***P < 0.001.