PDE4A and ischemia: [26]–[29] 2) cAMP has been reported to be responsible for neuron survival and a selective inhibitor of cAMP-specific phosphodiesterase type 4 (PDE4) can promote the survival of newborn hippocampal neurons after ischemia.[30]–[32] 3) SNP 83, which is located at the 5′ end of PDE4D, may affect the transcription, splicing, message stability, or message transport of one or more isoforms. [7].