Western blot analysis determines the responses of extracellular signal-regulated kinase (ERK), p-ERK and in wild-type (WT) fibroblast-like synoviocytes (FLS) to blockade of (Ca2+)
with cyclopiazonic acid ( CPA) and of protein phosphatase 2A (PP2A) with fostriecin (FOS). Responses after incubation in pH 6.0 were normalized to pH 7.4. (A) Pretreatment of WT FLS with CPA (30 μM) prior to application of pH 6.0 prevented the decrease in p-ERK when compared to WT FLS not treated with CPA (control) (P <0.05). (B) Blockade of PP2A with FOS (1000 nM) prevented the decrease in p-ERK in WT FLS treated with pH 6.0 when compared to WT FLS without FOS treated with pH 6.0 (control) (P <0.05).