SRSF9 is a serine/arginine-rich RNA-binding protein that functions as a modulator of alternative splicing with pleiotropic roles in disease. Mechanistically, SRSF9 regulates splicing through multiple pathways: it represses MAPT/Tau exon 10 inclusion and controls alternative splicing of target genes by recognizing RNA sequences and recruiting spliceosomal machinery 1. A distinctive feature is SRSF9's capacity to form phase-separated condensates via its RS domain, which enhances its splicing activity and is essential for its biological functions 23. Additionally, SRSF9 can interact with ADAR2 via its RRM2 domain to repress A-to-I RNA editing at brain-specific sites 4. Disease relevance spans multiple malignancies: SRSF9 promotes oral cancer by inducing oncogenic SLC37A4-S isoforms and conferring chemotherapy resistance 2, ovarian cancer progression through NUMB isoform switching 3, hepatocellular carcinoma proliferation via Wnt/cell cycle pathways 5, and glioblastoma growth by enhancing CDK1 expression 6. In cardiovascular disease, SRSF9-mediated NFATc4 splicing drives cardiac hypertrophy and heart failure 7. Conversely, SRSF9 suppresses HIV-1 production by inducing imbalanced viral mRNA splicing 8. Clinically, elevated SRSF9 expression correlates with poor prognosis in multiple cancers and represents a therapeutic target, with antisense oligonucleotides and phase separation inhibitors showing promise 235.