Fig. 2

Hypobaria exposure increases markers of cell cycle activation at 24 h after TBI. a Representative immunoblots for cell cycle-related proteins (cyclin D1, PCNA, and CDK4) and the loading control (GAPDH). b–d Expression levels of cell cycle proteins were normalized by GAPDH, as estimated by optical density measurements, and expressed as a percentage of sham tissue. At 24 h post-injury, a significant increase in the protein expression of cyclin D1, PCNA, and CDK4 was observed in the TBI/no-HB exposure group in comparison to the sham injury group. HB exposure following TBI significantly increased the protein expression of all three markers in comparison to the TBI-alone group. A significant decrease in the protein expression of all three markers was observed in the CR8 treatment group in comparison to the TBI/Veh/HB group. N = 7 (sham), 9 (TBI), 10 (TBI/Veh/HB), 7 (TBI/CR8/HB). *p < 0.05, ***p < 0.001, TBI vs. sham injury; ^# p < 0.05, ^### p < 0.001, TBI/Veh/HB vs. TBI/no-HB; ^$ p < 0.05, ^$$$ p < 0.001, TBI/CR8/HB vs. TBI/Veh/HB