TGFB1 and neoplasm: It is debatable whether Th17 cells play a positive, negative, or neutral role in tumor progression (Martin et al. 2012, Punt et al. 2016, Asadzadeh et al. 2017), but Jiao et al. (2019) made the point that these TGFβ-induced CD4+ Th17 cells might serve as a neutral pool of CD4+ T cells from which effector Th1 cells might differentiate under the influence of TGFβ blockade therapy.