Dramatic conversion of the agonistic activities of VB22B antibody against TPO dependent cells. (A) Structure models of minibodies, diabody, and sc(Fv)2. (B) Proliferative activities of anti-Mpl antibodies, VB22B whole IgG, diabody, sc(Fv)2, and rhTPO on both BaF/human Mpl (left panel) and BaF/monkey Mpl (right panel).