SNRPD1 (small nuclear ribonucleoprotein D1 polypeptide) is a core spliceosomal component essential for pre-mRNA splicing. It functions as a structural protein within U1, U2, U4, and U5 small nuclear ribonucleoproteins (snRNPs), participating in both precatalytic and catalytically active spliceosome complexes 1. SNRPD1 acts as a charged protein scaffold promoting snRNP assembly and strengthening inter-snRNP interactions through electrostatic contacts with RNA 2. Additionally, it contributes to U12-type intron splicing through the minor spliceosome 3. Beyond splicing, SNRPD1 plays critical roles in cellular differentiation and cancer biology. It is significantly upregulated during pluripotent stem cell reprogramming, where its depletion impairs pluripotency acquisition and maintenance 4. In disease contexts, SNRPD1 is aberrantly elevated and functions as an oncogene. High SNRPD1 expression correlates with poor prognosis in hepatocellular carcinoma, breast cancer, and gastric cancer 567. Mechanistically, SNRPD1 promotes tumor proliferation by suppressing autophagy through PI3K/AKT/mTOR pathway inhibition and regulating cell cycle progression via cyclin-dependent kinase activation 57. In triple-negative breast cancer, IGF2BP2-mediated m6A stabilization of SNRPD1 mRNA enhances its oncogenic functions 8. These findings establish SNRPD1 as both a fundamental spliceosomal protein and a potential therapeutic target in malignancies.