Antitumor activity of paclitaxel and triapine, alone or in combination, against Madison 109 murine lung carcinoma. Tumor-bearing mice (5 mice/group) were treated with i.p. injection of paclitaxel at a dose of 10 mg/kg once a day for 4 days, triapine isethionate salt (triapine ITS) at a dose of 10 mg/kg (equivalent to 6 mg/kg of triapine) twice a day, 8 h apart, for 4 days, or combination of both. Paclitaxel dissolved in DMSO at 10 mg/ml was injected in a volume of 10 µl/10 g weight using insulin syringes. Triapine ITS dissolved in water at 1 mg/ml (pH 4.5) was neutralized with 2 molar equivalents of NaHCO3 immediately before injection.