PDE1A and glioblastoma: Expression of A-kinase anchoring protein 1(AKAP1), which attaches PKA to the cytoskeleton, as well as phosphodiesterase 1A (PDE1A), a cAMP-degrading enzyme, were shown to be increased in glioblastoma specimens [75], whereas the catalytic subunit of PKA was found to be decreased in high-grade gliomas [76].