RBM4 (RNA binding motif protein 4) is a multifunctional RNA-binding protein containing two RNA recognition motifs and a zinc finger domain 1. Its primary function involves regulating alternative splicing and translation of target mRNAs through binding to pyrimidine-rich and CGCGCG[GCA] sequences. Mechanistically, RBM4 modulates muscle cell differentiation by antagonizing PTBP1 to promote exon skipping in tropomyosin and other transcripts 1. Under stress conditions, RBM4 recruits translation initiation factors to activate IRES-dependent translation while suppressing cap-dependent translation via 3'-UTR binding. RBM4 also facilitates miRNA-guided gene silencing by promoting AGO2-miRNP association with target mRNAs 1. Disease relevance is significant across multiple cancer types. In esophageal squamous cell carcinoma, elevated RBM4 promotes senescence evasion by degrading LKB1, enabling glutamine-dependent survival 2. RBM4 also mediates PD-L1 alternative splicing downstream of glycosylated SEMA7A in head and neck cancer 3. In renal cell carcinoma, RBM4 inhibition by the microprotein TPM3P9 enhances oncogenic TCF7L2-L splicing, promoting NF-κB signaling 4. Conversely, RBM4 acts as a tumor suppressor in gastric cancer by inhibiting proliferation and metastasis via MAPK pathway activation 5. Clinically, RBM4 expression correlates with patient outcomes and therapeutic response, making it a potential biomarker and therapeutic target across cancer types.