FIGURE 4.

Inhibition of PDGF-stimulated nuclear ERK by MRE-269 is dependent on cAMP. Nuclear ERK activity was measured in human lung fibroblasts electroporated with the nucEKAR FRET biosensor. Cells were stimulated with vehicle control (0.01% v/v acetic acid) or an EC₈₀ concentration of PDGF (10 ng/ml) with or without pre-incubation with 1 μM MRE-269 (n = 3). (A) No inhibitor treatment. (B) Pre-treatment with the adenylyl cyclase inhibitor, dideoxyadenosine (ddA, 30 μM). (C) Pre-treatment with the adenylyl cyclase inhibitor, SQ-22,536 (30 μM). (D) 30 min AUC calculated from A-C. **p < 0.01 and ***p < 0.001 vs. vehicle control, two-way ANOVA with Dunnett’s multiple comparisons test.