Effect of sin-1 on the generation of CFU-GM from canine (A) and human (B) LTMCs. Sin-1 was added every week beginning at the time of recharging. High concentrations of sin-1 (100 μg/mL) inhibited colony formation, whereas low concentrations (1 μg/mL) increased the numbers of CFU-GM (see text). The columns represent means ± SEM of three experiments (triplicate cultures each).