TGFB1 and neoplasm: Furthermore, tumor-associated macrophages (TAMs) are “pro-tumor” immune cells in high numbers in the TME [13] and are crucial in maintaining cancer stem cell (CSC) stemness; for instance, in breast cancer, TAMs can secrete regulatory mediators, including transforming growth factor-β1 (TGF-β1), to improve CSC epithelial-to-mesenchymal transition, prompting their tolerance to treatment pressures [14].