Fig. 1.

The survival of the CD34⁺ cells cultured in cytokine-free medium with or without irradiation. Non-irradiated or X-ray–irradiated CD34⁺ cells were seeded and cultured under serum- and cytokine-free conditions, as described in the Materials and Methods. After the indicated period of incubation, all cells cultured under each condition were harvested, and viable cells were counted by the trypan blue exclusion test. The values are the means ± standard deviation (S.D.) of more than three separate experiments performed in duplicate wells. *P < 0.05, by the Tukey–Kramer test.