TGFB1 and neoplasm: The “seed and soil” hypothesis provides a conceptual framework for this organotropism: bone serves as a fertile “pre-metastatic niche”, enriched with chemokines (like CXCL12 and TGF-β) and adhesion molecules (e.g., integrins, cadherins) that facilitate the homing and anchoring of circulating tumor cells [20].