SNRNP70 (U1-70K) is a core protein component of the U1 small nuclear ribonucleoprotein complex essential for both constitutive and alternative RNA splicing 1. Beyond its canonical role in spliceosome assembly and mRNA processing 1, SNRNP70 regulates chr19 retention of long noncoding RNAs through U1 snRNP-RNA interactions, functioning independently of splicing to tether lncRNAs to chr19 in a transcription-dependent manner 2. The protein contains RNA recognition motifs (RRM) critical for U1-snRNA binding; truncated isoforms lacking the RRM domain cannot bind U1-snRNA. SNRNP70 also participates in non-canonical miRNA biogenesis from intron-derived sequences 3. Clinically, SNRNP70 has emerged as a prognostic biomarker in multiple cancers. In osteosarcoma, elevated SNRNP70 correlates with poor prognosis and promotes tumor progression through CD55 alternative splicing modulation and immune cell infiltration 4. In hepatocellular carcinoma, SNRNP70 overexpression indicates poor outcomes, and nuclear SNRNP70 combined with serum AFP serves as a prognostic indicator 5. Additionally, specific SNRNP70 splicing alterations represent a molecular hallmark of an amyotrophic lateral sclerosis subtype 6, and SNRNP70 genetic variants associate with mixed connective tissue disease pathogenesis 7. These findings position SNRNP70 as both a fundamental splicing regulator and a disease-relevant biomarker.