It is transforming growth factor β (TGFβ) that is the master regulator of mechanisms of recruiting and transformation of normal fibroblasts into CAFs within the TME; this growth factor is produced by cancer cells and also by pro-tumor stromal cells such as Treg cells and M2 macrophages (Figure 3 and references [30,31]). The gene discussed is TGFB1; the disease is cancer.