Multiple GBM-derived factors are responsible for Tregs recruitment including CCL22, CCL2, TGF-β, or indoleamine 2,3-dioxygenase 1 (IDO1) (Akasaki et al., 2004; Akhurst and Hata, 2012; Wainwright et al., 2012; Chang et al., 2016). The gene discussed is IDO1; the disease is glioblastoma.