SNRPD3 (small nuclear ribonucleoprotein D3 polypeptide) is a core spliceosomal component essential for pre-mRNA splicing. It functions as part of the U1, U2, U4, and U5 small nuclear ribonucleoproteins, assembling into both pre-catalytic B and activated C spliceosomal complexes 12. SNRPD3 also participates in minor spliceosome-mediated splicing of U12-type introns 34 and histone pre-mRNA 3'-end processing via U7 snRNP. The protein undergoes symmetric arginine dimethylation by PRMT5, which is critical for preventing aberrant chr22 retention of transcripts and promoting mRNA nuclear export 5. SNRPD3 has emerged as a significant oncogenic factor across multiple cancers. In neuroblastoma, MYCN upregulates SNRPD3 expression to maintain alternative splicing fidelity required for tumor progression, and high SNRPD3 mRNA expression independently predicts poor patient outcomes 6. Similarly, SNRPD3 is significantly upregulated in endometrial cancer, where it promotes proliferation and metastasis by regulating SREBF1 mRNA splicing, with antisense oligonucleotide-based silencing showing therapeutic promise in patient-derived xenograft models 7. In hepatocellular carcinoma, SNRPD3 interacts with ADARp110 to stabilize CD24 mRNA, enhancing tumor immune evasion 8. A cancer-associated G96V mutation confers hypoxia resistance through altered splicing 9. Genome-wide screens identified SNRPD3 silencing as particularly effective for killing non-small cell lung cancer cells, with selective cytotoxicity compared to normal cells 10.