They further showed that conditioned media from breast cancer cells treated with metformin diminished the macrophage expression of M2-related cytokines (IL-8, IL-10, and TGF-β) and increased the macrophage expression of M1-related cytokines (IL-12 and TNF-α), and this translated to fewer M2-like and more M1-like macrophages in the tumors of the mice treated with metformin [84]. This evidence concerns the gene TGFB1 and breast cancer.