Fig. 5. Time-dependent inhibition of p44ERK activity during nitrogen-mediated anoxia and activation during recovery in RTHD fibroblasts. RTHD fibroblasts were exposed to nitrogen-induced anoxia and recovery for the indicated periods of time. Anoxia was obtained by flushing supplemented Leibovitz' L-15 with nitrogen until the oxygen was removed. Recovery occurred by incubating the cells in atmospheric air. (A) Top: western blot analysis of phospho-p44ERK during anoxia (N=3) and total p44ERK (N=1). Bottom: quantification of band intensity showed significant inhibition of p44ERK activity after 3 h, relative to the normoxic control (*P<0.05). (B) Top: western blot analysis of phospho-p44ERK during recovery (N=3) and total p44ERK (N=1). Bottom: quantification of band intensity showed recovery resulted in significant activation of p44ERK after 5 min, relative to anoxic cells (*P<0.05). The value at 120 min recovery was not significant (P=0.059) because of one very low experimental value.