Indeed, cancer cell-derived cytokines, such as transforming growth factor β (TGFβ) and interleukin (IL)-10 (Box 1), frequently skew the differentiation of tumor-infiltrating immune cells into a tumor-promoting phenotype (Flavell et al., 2010; Fridlender et al., 2009; Keirsse et al., 2017; Mantovani et al., 2002; Ondondo et al., 2013). Here, TGFB1 is linked to cancer.