SDCBP (syndecan binding protein), also known as syntenin-1 or MDA-9, is a multifunctional PDZ domain-containing adapter protein with diverse cellular roles 1. Primary functions include regulation of transmembrane protein trafficking, exosome biogenesis, and modulation of TGF-β signaling. SDCBP positively regulates TGFB1-mediated SMAD2/3 activation and epithelial-to-mesenchymal transition by enhancing TGFR1 cell-surface expression 2. It coordinates with SDC1/4 and PDCD6IP to regulate exosome biogenesis 3 and is consistently abundant in exosomes across multiple cell types, making it a putative universal biomarker 4. In cancer contexts, SDCBP promotes proliferation and metastasis across multiple tumor types 5. In pancreatic ductal adenocarcinoma, SDCBP inhibits YAP1 phosphorylation and proteasomal degradation, promoting tumor progression 6. In triple-negative breast cancer, SDCBP stabilizes BACH1 by disassembling SCF ubiquitin ligase complexes, enhancing metastatic gene expression 7. SDCBP also functions in immune regulation, with elevated expression identified as a diagnostic biomarker in asthma pathogenesis 8. Therapeutically, zinc pyrithione suppresses SDCBP-mediated PDAC progression, and SDCBP inhibition sensitizes cancer cells to combination therapies, positioning it as a promising therapeutic target across multiple malignancies.