FAM89B (family with sequence similarity 89 member B) functions as a regulatory protein involved in both TGF-β signaling inhibition and cytoskeletal regulation. According to UniProt annotations, FAM89B negatively regulates TGF-β-induced signaling by cooperating with SKI to prevent SMAD2 translocation from nucleus to cytoplasm in response to TGF-β. Additionally, it acts as an adapter protein that mediates specific recognition of LIMK1 by CDC42BPA and CDC42BPB in lamellipodia, facilitating LIMK1 activation and subsequent CFL1 phosphorylation important for lamellipodial F-actin regulation. Recent research has identified FAM89B as a potential diagnostic biomarker for glaucoma, where it showed significant downregulation under mechanical and swelling stress conditions, concurrent with PI3K/AKT pathway suppression 1. The study demonstrated that FAM89B exhibited robust biomarker properties with an area under the curve >0.7 in machine learning analysis 1. FAM89B's cellular localization in cytoplasm and lamellipodia supports its dual roles in transcriptional regulation and cell migration control. However, comprehensive mechanistic studies and clinical validation of FAM89B's functions remain limited in the current literature, warranting further investigation to fully characterize its biological significance.