Fig. 10. p44ERK is regulated at the level of MEK during chemical anoxia/recovery (A/R). Phosphorylation of MEK1 during A/R was analysed by western blotting (top) and phospho-specific bands were quantified (bottom). (A) Anoxia inhibits MEK in RTHD fibroblasts (N=4, *P<0.05). (B) Pre-treatment with 10 µmol l^–1 SB203580 for 1 h prevented inhibition of MEK during anoxia (N=3, *P<0.05). (C) Pre-treatment with 100 nmol l^–1 calyculin A (Cal. A) for 2 min blocked reactivation of MEK during recovery (N=4, *P<0.05).