Effect of inhibitors of calmodulin (Trifluoperazine, J-8, W-7) and the multifunctional Ca2+/calmodulin dependent protein kinase (KN-93). Hepatocytes were cultured for 3 h before preincubation with timolol (10 μM) for 30 min in the presence or absence of indicated inhibitors prior to stimulation for 5 min with norepinephrine (10 μM), PGF2α (10 μM) or A23817 (10 μM), before cells were harvested and ERK1/2 activation assessed. A: Pretreatment with trifluoperazine (50 μM) in 0.5 % DMSO. The results represent one typical experiment out of three and are expressed as percent of untreated control. B: Pretreatment with J-8 (10, 25, and 50 μM) in 0.5 % DMSO. The results represent mean ± S.E.M of three experiments and are expressed as percent of corresponding control values. C: Pretreatment with W-7 (100 μM) or KN-93 (20 μM) in 0.5 % DMSO, while the final DMSO concentration during incubation with agonist was 1 %. Results represent mean ± S.E.M. of five experiments and are expressed as percent of untreated control.