Figure 5. The proliferation of NPCs under normoxic and hypoxia-reoxygenation conditions.

For HR treatment, NPCs were exposed 1% to O₂ for 24 h and then switched to 21% O₂ for 1, 3, 7, and 14 days, while for normoxic treatment, NPCs were consistently cultured under normoxia with 21% O₂. A. Representative immunofluorescent imaging of Ki-67 in NPCs. Red color: Ki-67 staining; Nuclear localization of Ki-67 was verified by co-localization with DAPI staining (blue color). B. Statistical analysis on the relative percentage of Ki-67 positive cells in NPCs (Mean ± S.D., n = 6). Observed day versus day 1 under the same oxygen condition, ## p<0.01.