SMAD7 and inflammatory bowel disease: Novel inhibitors targeting cytokines (such as IL-12/23 inhibitors, phosphodiesterase-4 (PDE4) inhibitor), integrins (such as integrin inhibitors), cytokine signaling pathways (such as Janus Kinase Inhibitor (JAK), Mothers against decapentaplegic homolog 7 (SMAD7) blocker) and cell signaling receptors (such as sphingosine-1-phosphate receptor 1 (S1P) modulator) are the preferred approaches for treatment of IBD [46].