Effects of draflazine on TMTX toxicity in proliferating human myeloid progenitors. Mobilized peripheral blood CD34⁺ cells from two separate patients (nos. 2 and 5) were cultured in the presence of dialyzed FBS and cytokines. Cultures also contained 150 nmol/L TMTX, 100 μmol/L hypoxanthine, 1 μmol/L draflazine (amount of active stereoisomer), and differing amounts of thymidine (Thd) as indicated. After 4 days of culture, cells were washed and equal volumes of cells were plated in methylcellulose to determine the myeloid progenitor content. Progenitor survival is expressed as a percentage of CFU-C relative to TMTX-free conditions as in Fig 2. Dark and light bars represent the data obtained with samples from the two different patients. Each bar represents the mean of two experiments ±1 SD.