TGFB1 and plasma cell myeloma: The bone marrow microenvironment plays a crucial role in the progression of multiple myeloma by secreting a range of cytokines and growth factors (e.g., IL-6, VEGF, TGF-β, IGF-1, CXCL12) that support the survival, proliferation, and resistance to apoptosis of myeloma cells [191].