Fig. 4

Effects of the dopamine D₁ receptor agonist A68930 on the phosphorylation of CREB in cultured airway epithelial cells. Cells were stimulated with A68930 (1 μM), and subsequently cell lysates were processed to detect phosphorylated (upper panels) and total (lower panels) levels of CREB by immunoblot. a Representative immunoblot analyses of the time-course effect of the dopamine D₁ receptor agonist A68930 (1 μM) on CREB phosphorylation in cultured (i) 16HBE14o- cells and (ii) NCI-H292 cells. Phosphorylated activating transcription factor 1 (ATF-1) is a CREB family member that is also recognized by the phospho-CREB antibody and closely correlates with CREB [13]. b Effect of A68930 (1 μM, 20 min) on CREB phosphorylation in (i) 16HBE14o- cells (n = 3) and (ii) NCI-H292 cells (n = 7). c Effects of inhibitors of PKA or MEK on A68930-stimulated CREB phosphorylation in NCI-H292 cells (n = 4). Cells were pretreated with the PKA inhibitor H89 (10 μM, 30 min), or the MEK inhibitor U0126 (5 μM, 120 min) before treatment with A68930 (1 μM, 20 min). Data represent means ± SEM. *P < 0.05 compared with basal. ^#P < 0.05 and ^###P < 0.001 compared with A68930 alone