SMNDC1 (survival motor neuron domain containing 1) is a nuclear splicing factor that plays crucial roles in RNA processing and gene regulation. The protein is involved in spliceosome assembly and functions within nuclear bodies and nucleoplasm 1. SMNDC1 contains a conserved autoregulatory poison exon that undergoes alternative splicing to control protein levels through nonsense-mediated mRNA decay, with this mechanism being conserved across mammals and plants 2. Loss of this autoregulatory mechanism leads to SMNDC1 protein deregulation, altered mRNA processing, and organismal growth restriction 2. In pancreatic cells, SMNDC1 acts as a repressor of insulin expression by modulating chr10 remodeling complexes (BAF and Atrx) and suppressing the β cell transcription factor Pdx1 3. The protein shows elevated expression in various cancers, including ovarian and hepatocellular carcinoma, where it promotes cell proliferation and migration 45. SMNDC1 is also involved in the PRMT5 signaling pathway and shows positive correlation with immune cell infiltration in tumors 65. Additionally, it has been identified as an apoptosis-related protein that becomes upregulated during certain cytotoxic processes 7.