DCP1B (decapping mRNA 1B) is a non-redundant cofactor of the mRNA cap hydrolase DCP2 that plays specialized roles in mRNA decapping and post-transcriptional gene regulation 1. DCP1B enhances mRNA-binding affinity through its EVH1 domain and is essential for decapping complex interactions with protein degradation and translational machinery, distinct from its paralog DCP1a which mediates decapping complex assembly 12. DCP1B regulates the turnover of specific mRNA targets, including MAPK4 mRNA 3. Functionally, DCP1B acts as a tumor suppressor gene transcriptionally activated by p53 in non-small cell lung cancer; it inhibits cell growth and migration by promoting MAPK4 mRNA decay, thereby suppressing AKT signaling and enhancing PI3K inhibitor sensitivity 3. Additionally, DCP1B is implicated in memory performance through microRNA-138 regulation of its 3' UTR expression in brain tissues 4, and genetic variants in DCP1B are associated with diabetic retinopathy 5 and amblyopia, suggesting neurodevelopmental functions 6. DCP1B localizes to P-bodies and participates in viral RNA decay during flavivirus infection 7, highlighting its broader role in cellular RNA metabolism.