ALDH7A1 and glioblastoma: Using microarray gene expression data from GBM cell lines,24 transcriptome analysis of all four GBM cell lines used in our study revealed overexpression of three key PDE family members (PDE2A, PDE5A, PDE10A; Figures 6c and d) in the cAMP agonist-sensitive cells, T98G and A172.