SUGP1 (SURP and G-patch domain containing 1) is a G-patch protein that plays a critical role in pre-mRNA splicing quality control. Functionally, SUGP1 acts as a regulatory factor that activates the DExH-box helicase DHX15 to promote splicing fidelity by triggering early spliceosome disassembly in response to kinetic blocks 1. SUGP1 specifically recruits DHX15 to suppress suboptimal introns with weak splice sites and cryptic introns, preventing their incorporation into mature transcripts 2. The protein contains a U2AF ligand motif (ULM) domain essential for DHX15 interaction 2. Clinically, SUGP1 dysfunction is implicated in cancer pathogenesis. Loss of SUGP1 recapitulates nearly all splicing defects induced by oncogenic SF3B1 hotspot mutations, the most frequently mutated splicing factor in cancer 3. SF3B1 mutations disrupt SUGP1 interaction, leading to aberrant 3' splice site usage and widespread missplicing 4. Additionally, SUGP1 genetic variants (rs10401969) associate with alcohol-related cirrhosis risk when combined with other genetic factors and diabetes status 5. The discovery that SUGP1 loss drives SF3B1-mutant missplicing establishes SUGP1 as a fundamental regulator of splicing accuracy and a potential therapeutic target in SF3B1-mutant malignancies.