Recently, Garo et al. demonstrated SMAD-dependent PD-L1 regulation by TGF-β in a colitis model relevant to IBD, where signaling through SMAD2 was critical to increased PD-L1 expression, while the activation of SMAD7, an inhibitor of TGF-β canonical signaling pathway, downregulated PD-L1 [52]. This evidence concerns the gene TGFB1 and inflammatory bowel disease.