FIGURE 5.

Effects of PKA activation (P-PKA substrates) on the Ser²³ α1 subunit (P-S23-α1) and ERK phosphorylation (P-ERK). Parotid acinar cells were treated with isoproterenol (Iso, 10⁻⁵ m, 1 min) and forskolin (Fsk, 10 μm, 10 min) prior to carbachol (10⁻⁵ m, 2 min) and PMA (100 nm, 2 min). A and B, cell lysates were analyzed by Western blot as indicated. C, the phosphorylation of α1 subunit on Ser²³ (S23 Alpha) was quantified relative to basal conditions (no additions). n = 4 (carbachol) or 3 (PMA). *, p < 0.05 versus basal (no additions).