RBCs respond to β-adrenergic receptor activation with the phosphorylation of CREB-like proteins. Western blot analysis of day-11 RBCs before (t₀) and during a one-hour incubation with 1 μM NE and 10 μM propranolol (P). The RBC proteins (200 μg Hb per lane) in the MW range of 42 to 46 kDa were analyzed with antibodies specific for phosphorylated forms of CREB/cAMP response element modulator (CREM)/activating transcription factor 1 (ATF1) proteins (upper blot). As a control, we also detected the total amount of CREB proteins with specific antibodies (lower blot). Shown is 1 of 3 experiments.