TGFB1 and neoplasm: In addition, MDSCs, also called "natural suppressor cells", accumulate under the influence of diverse tumor-derived factors, such as VEGF, TGF-β1, ILs, and PGE2; MDSCs not only inhibit a variety of immune effectors, especially CD4+ and CD8+ T lymphocytes, but also transform into osteoclasts, which promote tumor progression and tumor-induced bone loss [21,141].