Effect of cAMP effectors on the βAPP mRNA and protein expressions in HEK293 cells. Stably transfected HEK293 cells overexpressing wtβAPP751 were obtained, cultured, and treated for 7 hr at 37°C without (control) or with dideoxyforskolin (DDF, 20 µM), forskolin (20 µM), or dibutyryl cAMP (dBut-cAMP, 1 mM) as described in Materials and Methods. Total mRNA was extracted, denaturated, and electrophoresed as described in Materials and Methods. Ribosomal mRNA (A) were visualized by UV and βAPP mRNAs (B) were revealed by means of a radiolabeled specific cDNA probe. Expression of immature and mature full-length βAPP (βAPPFL) was analyzed by Western blot with WO2 antibody (C) as described in Materials and Methods. Panel D corresponds to the densitometric analysis of the βAPP immature and mature 110 and 140 kDa immunoreactive bands. Values are expressed as the percent of the control densitometry obtained in untreated cells and the mean ± SEM of four independent determinations.