RSF1 (remodeling and spacing factor 1) is a regulatory subunit of ATP-dependent chr11 remodeling complexes that plays crucial roles in chr11 organization and transcriptional regulation 1. The protein functions as part of RSF-1 and RSF-5 ISWI complexes to form ordered nucleosome arrays and facilitate DNA access during replication, transcription, and repair processes. In DNA damage response, RSF1 is recruited to DNA double-strand breaks with a half-time of ~100 seconds and remains for ~2000 seconds, coinciding with early chr11 remodeling events 2. RSF1 orchestrates p53-dependent transcription by coordinating p300 acetyltransferase recruitment and FACT complex assembly at target gene promoters, promoting p53 acetylation at Lys382 1. Clinically, RSF1 demonstrates oncogenic properties across multiple cancer types. In myxofibrosarcomas, RSF1 overexpression promotes angiogenesis through IL-1β upregulation via CEBP/β-mediated transcriptional activation 3. RSF1 amplification on chromosome 11 occurs in breast cancers and may predict tamoxifen resistance 4. The gene is regulated by microRNAs including miR-193b-3p and miR-193a-3p in esophageal and osteosarcomas respectively, where RSF1 upregulation correlates with poor prognosis and enhanced tumor progression 56.