Figure 4. Improvement in intracellular functions of hypoxia-exposed RPC-C2A-K4 cells by re-oxygenation. After the cells were exposed to hypoxia for 24 hrs, cells were incubated under a normoxic condition (re-oxygenation). (A) Cell viability was monitored by MTT assay. Data are expressed as the mean ± SD of triplicate cultures. The experiment was performed 3 times, with similar results obtained in each experiment. Statistical differences were determined between the cells exposed to 24 hrs of hypoxia (0 hr after re-oxygenation) and the cells exposed to normoxia after 24 hrs of hypoxia (a, 12 hrs of re-oxygenation; b, 24 hrs of re-oxygenation; c, 36 hrs of re-oxygenation). *p < 0.01. (B) DNA content was analyzed by flow cytometry. Non-treated, cells in normoxia. (C) Expression of cyclin D2 in re-oxygenated RPC-C2A-K4 cells.