Mice deficient for SHP-1 or Btk respond to IVIg treatment of ITP. Mice were treated as described in Figure 1A. (A) Littermate control (○), SHP-1-deficient (me/me; ▿) mice; n = 6 except for day 4, where n = 3 for SHP-1-deficient mice. (B) Btk KO (▿) and control wild-type (○) mice (C57BL/6) were treated as in Figure 1A; n = 10 mice/data point. Data are expressed as mean ± SEM.