CELF6 (CUGBP Elav-like family member 6) is an RNA-binding protein that regulates both alternative splicing and mRNA stability with significant roles in cellular proliferation and neural function. CELF6 mediates tissue-specific alternative splicing by activating exon inclusion in cardiac troponin T through muscle-specific splicing enhancers and promoting exon exclusion in insulin receptor pre-mRNA 1. Beyond splicing regulation, CELF6 functions as a tumor suppressor by stabilizing p21 mRNA through binding to its 3' UTR, leading to G1 phase arrest and reduced cell proliferation 2. In cancer contexts, CELF6 suppresses proliferation in triple-negative breast cancer by stabilizing FBP1 mRNA 3 and in lung cancer by downregulating immune-related genes that promote tumorigenesis 4. CELF6 protein levels are regulated through ubiquitin-proteasome degradation, with MDM2 serving as a key E3 ligase promoting its degradation 5. In the nervous system, CELF6 destabilizes synaptic gene mRNAs through 3' UTR interactions, affecting proteins like FOS and FGF13 6, and its loss impairs conditioned learning behaviors including cocaine preference and contextual fear conditioning 7. The protein is highly expressed in brain, kidney, and testis, with widespread brain expression maintained from fetal to adult stages 1.