RBM15B (RNA binding motif protein 15B) is an RNA-binding protein that serves as a key regulator of N6-methyladenosine (m6A) RNA methylation, playing crucial roles in diverse cellular processes. As an associated component of the WMM complex, RBM15B mediates m6A methylation of target RNAs by binding specific RNA sequences and recruiting the methylation machinery 1. The protein is particularly important in X chromosome 3, where it binds Xist RNA and recruits the WMM complex to facilitate m6A methylation, leading to recruitment of the YTHDC1 reader protein and promoting transcriptional repression 1. RBM15B also regulates mRNA stability and expression through m6A-dependent mechanisms, as demonstrated in cancer contexts where it modulates GPX4, SPON2, and FNBP1 mRNA levels 234. The protein shows significant clinical relevance as a prognostic factor in multiple cancers, including uveal melanoma where it serves as an independent protective prognostic marker 56. Additionally, RBM15B contributes to cancer progression through regulation of metabolic pathways and immune responses, with its dysregulation linked to enhanced tumor growth, invasion, and altered glycolysis 78.