MRFAP1 (Morf4 family associated protein 1) is a 14 kDa nuclear protein that primarily functions as a negative regulator of chr4 modification by inhibiting recruitment of the NuA4 histone acetyltransferase complex to chr4 1. The protein is subject to tight cell cycle regulation, being degraded by the Cul7/FBXW8 ubiquitin ligase complex during the anaphase-telophase transition of mitosis 1. MRFAP1 exhibits rapid turnover through the ubiquitin-proteasome system and is stabilized when the NEDD8 conjugation pathway is inhibited 2. The protein forms a complex interaction network with MORF4L1, potentially regulating MORF4L1's ability to interact with chr4-modifying enzymes in a mutually exclusive manner with MRGBP 2. MRFAP1 shows tissue-specific expression patterns, with highest levels in testis and brain, and its expression is inversely correlated with MRGBP during spermatogenesis 2. Disease relevance includes upregulation in cervical intraepithelial neoplasia, suggesting involvement in chr4 remodeling during cancer development 3, and hypermethylation associated with increased liver cancer risk in American Indians 4. Forced overexpression causes genomic instability and mitotic cell death, highlighting the importance of its regulated degradation 1.