3 hour intravenous infusion as a dose of either 54 mg/m2 or 128 mg/m2 daily for 5 days every three weeks.

Human lung cancer Calu-6 cells were used for activity evaluation. 1×10^4 cells per well were seeded in 96-well microtiter plates (Nunc). After incubation with the 1, 2, 3, 4 and 5 mkM of PX-12 (DB05448) for the 72 h, MTT solution [20 μl; 2 mg/ml in phosphate-buffered saline (PBS)] was added to each well of the 96-well plates. The plates were additionally incubated for 3 h at 37 °C. Medium was removed from the plates by pipetting, and 200 μl DMSO was added to each well to solubilize the formazan crystals. The optical density was measured at 570 nm using a microplate reader (Synergy™ 2, BioTek Instruments Inc., Winooski, VT, USA).