PDE4A (phosphodiesterase 4A) is a cAMP-specific phosphodiesterase that efficiently hydrolyzes cyclic adenosine monophosphate (cAMP), thereby regulating intracellular cAMP signaling 1. The enzyme functions as a critical negative regulator of the cAMP/PKA signaling pathway, with multiple splice variants generated through alternative mRNA splicing and promoter usage 21. PDE4A localizes to the perinuclear cytoplasm and plasma membrane, where it modulates G protein-coupled receptor signaling 1. In disease contexts, PDE4A plays important roles in inflammatory processes and cancer progression. GWAS studies have identified PDE4A as a potentially druggable target for COVID-19 critical illness, specifically in regulating monocyte-macrophage activation and endothelial permeability 3. In cancer, PDE4A is regulated by pSTAT3 in chemotherapy-resistant inflammatory breast cancer cells, where it contributes to elevated cAMP signaling and therapeutic resistance 4. The enzyme is also implicated in various cancer types as part of the PDE4 subfamily's emerging role in malignancy 5. Additionally, PDE4A expression can be dynamically regulated by elevated cAMP levels, with forskolin treatment causing downregulation of specific PDE4A splice variants in T-cells 6.