Figure 4
Effect of intermittent hypoxia (IH)-induced ROS generation on PP2A activation and downregulated ERK1/2 activation leading to PC12 cell proliferation inhibition. (A) PC12 cell numbers determined by MTT assay after exposure to normoxia for 4 days (RA4, control, n = 16), and RA4 along with the ERK1/2 phosphorylation inhibitors U0126 (n = 8) and PD98059 (n = 7), the ERK1/2 phosphorylation activator nicotine (n = 14), and exposed to IH for 4 days (IH4, control, n = 8), IH4 along with superoxide dismutase (SOD, n = 12), the PP2A activation inhibitors 1,10-phenanthroline (Phe, n = 12), okadaic acid (OKA, n = 9) and cantharidin (Can, n = 9) and nicotine (n = 9). (B) PC12 cell proliferation determined by BrdU cell proliferation ELISA assay kit after exposure to RA4 (n = 8), IH4 (control, n = 8) and IH4 along with SOD (n = 7), Phe (n = 7), OKA (n = 7), Can (n = 7) and nicotine (n = 6). (C) Percentages of PC12 cells in G0/G1 phase arrest as determined by propidium iodide staining and flow cytometry after exposure to RA4 (control, n = 8), RA4 along with U0126 (n = 4), RA4 with nicotine (n = 4), IH4 (control, n = 7), IH4 along with SOD (n = 6), Phe (n = 5), OKA (n = 5) and nicotine (n = 4). *p < 0.05 compared with RA4. #p < 0.05 compared with IH4. Values are means ± SEMs.