Ligation of CD28 stimulates the formation of a multimeric signaling complex involving grb-2-associated binder 2 (gab2), SRC homology phosphatase-2, and phosphatidylinositol 3-kinase: evidence that negative regulation of CD28 signaling requires the gab2 pleckstrin homology domain.
Parry RV, Whittaker GC, Sims M, Edmead CE, Welham MJ, Ward SG. J Immunol. 2006 Jan 1; 176(1):594-602.