TGFB1 and neoplasm: On the other hand, the hypoxic microenvironment in tumors attracts inflammatory cells and immunosuppressive cells such as tumor-associated macrophages (TAMs)12, myeloid-derived suppressor cells (MDSCs)13 and regulatory T cells (Treg cells)14, and those cells through paracrine many cytokines factors, such as IL-6, IL10, EGF, SCF, TNF-α and TGF-β, which can increase and enrich CSLCs through continuous activation of pluripotent and self-renewal pathways such as the Hedgehog, Notch and Wnt/β-catenin pathways15, 16, 17, 18.