The effects of nucleoside transport inhibitors on TMTX killing of murine progenitors. Unseparated murine BM cells were added to in vitro suspension cultures containing cytokines, dialyzed FBS, hypoxanthine, TMTX, and thymidine (Thd) in various amounts as indicated. Each panel shows data from cultures which also contained the indicated concentrations of one of the following nucleoside transport inhibitors: NBMPR, draflazine (amount of active stereoisomer), or dipyridamole. Equal volumes of cells were plated in methylcellulose after 4 days of suspension culture to determine the myeloid progenitor content. Progenitor survival is expressed as a percentage of CFU-C relative to TMTX-free conditions as described in Fig 2. Each bar represents the mean ±1 SD for three independent experiments.