TSSC4 is a nuclear protein with dual roles in RNA splicing and cancer suppression. Structurally, TSSC4 is an intrinsically disordered protein that functions as a U5 snRNP assembly and recycling factor 12. It employs conserved regions to bind PRPF8 and SNRNP200 helicase, inhibiting SNRNP200 activity while coordinating U5 snRNP assembly into the functional U4/U6•U5 tri-snRNP complex 23. Beyond spliceosomal function, TSSC4 suppresses cancer through splicing regulation and autophagy inhibition. TSSC4 deficiency causes widespread alterations in alternative splicing patterns and dysregulates tumor-associated genes including oncogenes across multiple cancer cell lines 4. Additionally, TSSC4 inhibits autophagy via interaction with MAP1LC3/LC3, preventing cancer cells from entering death pathways during proliferation 5. This dual mechanism is clinically relevant: TSSC4 suppresses glioblastoma and breast cancer growth, with its expression promoted by oncogenic EGFR and ERBB2 variants 5. A two-gene classifier including TSSC4 achieved 100% accuracy in distinguishing allergic asthma from controls 6, suggesting potential diagnostic applications. TSSC4 is located in the imprinted 11p15 region but itself escapes genomic imprinting 7.