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TGF-β1 （Transforming Growth Factor-beta 1） is a multifunctional cytokine belonging to the TGF-β superfamily, playing a pivotal role in cell proliferation, differentiation, apoptosis, immune regulation, extracellular matrix formation, and tissue repair. Synthesized as an inactive precursor, it undergoes proteolytic activation to form a biologically active homodimer. TGF-β1 signals through binding to TGF-β receptors （Type I/II）, triggering both Smad-dependent （canonical） and Smad-independent （non-canonical, e.g., MAPK, PI3K） pathways. Critical in embryogenesis, wound healing, and fibrosis, TGF-β1 exhibits dual roles in disease—acting as a tumor suppressor early in cancer but promoting metastasis in advanced stages. Dysregulation is linked to fibrotic disorders （e.g., pulmonary fibrosis）, autoimmune diseases, and cancer progression. Its context-dependent functions （anti-inflammatory vs. pro-fibrotic/tumorigenic） are influenced by microenvironmental cues, making it a therapeutic target for fibrosis, cancer, and inflammatory conditions.