ARPP21 (cAMP regulated phosphoprotein 21) is an RNA-binding protein that plays important roles in neuronal function and development. The protein demonstrates high specificity for binding uridine-rich sequences in 3'UTRs of target mRNAs 1. ARPP21 functions as a positive post-transcriptional regulator by interacting with the translation initiation complex eIF4F to enhance protein synthesis 1. A key regulatory mechanism involves ARPP21 antagonizing its intronic miRNA miR-128, where both products co-regulate overlapping target mRNAs enriched for neurodevelopmental functions 1. This antagonistic relationship has functional consequences during dendritogenesis, with ARPP21 overexpression increasing dendritic complexity while miR-128 overexpression or ARPP21 knockdown reduces it 1. In stroke pathology, ARPP21 promotes neurological function repair by upregulating CREB1 and BDNF expression through miR-128 antagonism, inhibiting neuronal apoptosis and facilitating astrocyte proliferation 2. Recent genetic studies have identified ARPP21 variants in amyotrophic lateral sclerosis patients, suggesting potential involvement in motor neuron degeneration 34. The protein appears to be important for maintaining neuronal health and proper neurodevelopmental processes through its RNA-binding and translational regulatory activities.