The Grb2-associated binding protein 2 (Gab2), which plays a role in regulating the activation of macrophages and T cells, and Grb2-associated binding protein 3 (Gab3), which is highly expressed in some immune cell types, redundantly regulate the activation of macrophages and CD8+ T cells to inhibit colitis (Uno et al., 2010; Bezman et al., 2012; Best et al., 2013; Festuccia et al., 2014; Kaneda et al., 2016; Wang et al., 2019; Ma et al., 2020b). The gene discussed is GAB2; the disease is colitis.