CELF1 (CUGBP Elav-like family member 1) is an RNA-binding protein that regulates multiple post-transcriptional processes critical for cellular function and disease pathogenesis. The protein binds to diverse RNA sequences including CUG triplet repeats, AU-rich elements, and Bruno response elements to control alternative splicing, mRNA stability, and translation 1. CELF1 demonstrates sequence-specific RNA binding with structural preferences, showing inhibited binding when RNA adopts secondary structures 1. In disease contexts, CELF1 functions as a tumor promoter in oral squamous cell carcinoma, where it protects cells against oxidative damage and promotes tumor growth through extensive transcriptome remodeling affecting 1283 mRNAs 2. The protein plays protective roles in metabolic regulation by stabilizing Dio2 mRNA to promote white fat beiging and thermogenesis, with reduced expression correlating with obesity 3. CELF1 contributes to Alzheimer's disease pathogenesis through regulation of KLC1 alternative splicing, where decreased CELF1 levels lead to increased production of the pathogenic KLC1 variant E 4. Additionally, CELF1 participates in X-chromosome 11 by forming condensates with other RNA-binding proteins on Xist RNA, contributing to heritable gene silencing mechanisms 5. The protein also maintains intestinal epithelial barrier integrity through post-transcriptional regulation of tight junction proteins 6.