TGFB1 and breast cancer: This cytokine, together with transforming growth factor (TGF)-β or interleukin (IL)-10, can be produced by suppressive cell populations, such as MDSCs [28,29,30] or M2-like tumor associated macrophages (TAMs) to promote disease progression in BC patients via bone metastases and epithelial–mesenchymal transition [31,32,33], as shown in Figure 1.