YY1 (Yin Yang 1) is a multifunctional transcription factor that serves as a structural regulator of chr14 architecture and gene expression. YY1's primary function involves forming enhancer-promoter loops through homodimer formation, analogous to CTCF-mediated interactions, where it binds to active enhancers and promoter-proximal elements to facilitate long-range DNA interactions essential for mammalian gene control 1. Mechanistically, YY1 operates through multiple pathways: it can function as both a transcriptional activator and repressor depending on context, with its C-terminal domain (residues 296-414) responsible for transcriptional activation 2. YY1 also undergoes liquid-liquid phase separation when complexed with HDAC1/3, which modulates its transcriptional activity and target gene expression 3. The protein's stability is regulated by the ubiquitin-proteasome system, with OTUD3 serving as a key deubiquitinase that prevents YY1 degradation 4. YY1 has significant disease relevance, particularly in cancer where it promotes tumor progression by cooperating with other factors to drive oncogene expression 5 and modulating drug sensitivity 6. Additionally, YY1 plays a critical role in extrachromosomal DNA biogenesis through DNA looping and religation mechanisms 7. Clinically, YY1 expression levels correlate with patient prognosis in various cancers, making it a potential therapeutic target.