INTS9 is a core component of the Integrator complex, a multiprotein assembly that regulates RNA polymerase II (Pol II) transcription termination and non-coding RNA processing 1. As part of the catalytic INTS4-INTS9-INTS11 cleavage module, INTS9 facilitates three mechanisms of transcription control: dephosphorylation of Pol II's C-terminal domain, endonucleolytic degradation of nascent transcripts, and Pol II release from DNA 2. INTS9 interacts stably with INTS11 through conserved C-terminal domains essential for snRNA 3'-end processing and controls expression of non-coding RNAs including enhancer RNAs, snRNAs, and lncRNAs 2. INTS9 forms a functional trimeric complex with INTS11 and BRAT1, a cytoplasmic chaperone that stabilizes and facilitates nuclear import of the endonuclease module 3. Assembly of the mature INTS9-containing cleavage module requires inositol hexaphosphate (IP6) as an essential cofactor, with BRAT1 and WDR73 serving as critical biogenesis factors 1. Clinically, mutations disrupting INTS9 interactions with BRAT1 or INTS11 impair Integrator function and cause neurodevelopmental and neurodegenerative disorders characterized by defects in RNA processing, neuronal differentiation, and REST-responsive gene activation 456.