cAMP-dependent stimulation of βAPP maturation products is not affected by actinomycin D in wtβAPP751-expressing HEK293 cells. Stably transfected HEK293 cells overexpressing wtβAPP751 were preincubated for 1 hr with actinomycin D (5 µg/ml) then incubated and metabolically labeled with actinomycin D in the absence (control) or presence of the indicated cAMP agonists. Intracellular βAPP immunoreactivity was revealed with WO2 (A) while Aβ40 (B), Aβ42 (C), and APPα (E) were immunoprecipitated as described in the Figure 2. Densitometric analysis of gels radioautographies of Aβs (D) and APPα (F) are expressed as the percent of control densitometry obtained in the absence of effector and are the means of three to four independent experiments. Densitometric analysis of the three bands of βAPP in panel A indicate a mean value (expressed as the percent of control) of (upper band) 110, 88.5 and 103.5; (middle band) 107, 88 and 101; (lower band) 117, 101, and 106 for DDF, forskolin and dBut-cAMP, respectively.