Fig 1: PDE4D inhibition dose-dependently increased CREB phosphorylation and neurite length in N2a cells. A Phosphorylated CREB (pCREB) to total CREB ratios in N2a cells upon treatment with 0.03–1.0 µM GEBR32a for 1 h (Dunnett's post-hoc: *P < 0.05, ***P < 0.001; n = 6/condition). Representative blot scans are shown under the graph. B Average neurite after incubation with 0.1–1.0 µM GEBR32a for 48 h in N2a cells (Dunnett’s post-hoc: **P < 0.01; n = 6/condition). C Exemplary microscope images indicating N2a neurites in the DMSO (left) and 1.0 µM GEBR32a (right) conditions that were visualized for subsequent tracing. Data is presented as mean + SEM