RBBP4 is a histone chaperone and core component of multiple chr1-regulatory complexes that governs histone H3 and H4 behavior 1. As a component of chr1 assembly factor 1 (CAF-1), RBBP4 facilitates chr1 assembly following DNA replication and repair 2. It functions within the nucleosome remodeling and deacetylase (NuRD) complex to promote transcriptional repression through histone deacetylation and nucleosome remodeling 34, and serves in the polycomb repressive complex 2 (PRC2) to regulate homeotic gene repression during development 5. RBBP4 also interacts with histone acetyltransferase p300 to activate pro-survival genes 6. Disease relevance is substantial: RBBP4 upregulation promotes glioblastoma chemotherapy resistance by regulating DNA double-strand break repair through the Mre11-Rad50-NBS1 complex 7. In acute myeloid leukemia, RNF5-mediated ubiquitination of RBBP4 drives disease maintenance and reduces sensitivity to histone deacetylase inhibitors 8. RBBP4 downregulation increases cisplatin sensitivity in lung and cervical cancer by inhibiting cyclin D1 9. In neural progenitors, RBBP4 loss disrupts cell cycle progression and triggers p53-dependent apoptosis via altered p53 acetylation 10. These findings position RBBP4 as a critical epigenetic regulator with significant therapeutic potential across multiple cancer types.