SMAD4 and neoplasm: Enriched in PC3-ML cells, exosomal miR-888 downregulates important proteins such as Krüppel-like factor 5 (KLF5), retinoblastoma-like protein 1 (RBL1), tissue Inhibitor of metalloproteinases 2 (TIMP2), and SMAD family member 4 (SMAD4), enhancing overall tumor cell capabilities (99).