In this mini review we aim to highlight the important role of these enzymes in pituitary diseases, especially the PDE4A4/5 isoform, encoded by the PDE4A gene, which has been implicated in GH-secreting adenomas due to its selective interaction with aryl hydrocarbon receptor-interacting protein (AIP), a known tumor suppressor gene (5). The gene discussed is AIP; the disease is pituitary gland disorder.