YBX3 (Y-box binding protein 3) is an RNA-binding protein that functions primarily as a regulator of mRNA stability and translation. YBX3 contains a highly conserved cold-shock domain and binds to specific RNA sequences, particularly the 3'-UTR regions of target mRNAs 1. The protein exhibits dual functions in cellular regulation: it can enhance mRNA stability and translation of certain targets like SPRED1 through direct binding to CACAUC motifs 2, while also promoting degradation of others such as SLC7A11 3. YBX3 expression varies significantly across cancer types and is associated with tumor progression through multiple mechanisms 1. In B cell development, YBX3 expression reciprocally correlates with transcription factor EBF1 during pre-BCR-dependent proliferative phases 4. The protein plays critical roles in immune evasion, with depletion leading to enhanced antigen presentation and pro-inflammatory gene expression 5. YBX3 is regulated by various mechanisms including protein stabilization through TTC36 binding that prevents proteasomal degradation 2, and interaction with long non-coding RNAs like HEIH and PIG13-DT that affect its stability and function 16. Clinically, YBX3 expression correlates with tumor grading, immune therapy responses, and drug resistance patterns across multiple cancer types.