PSTPIP2 deficiency in macrophages, mast cells, and osteoclasts of cmo mice is associated with splenomegaly and increased numbers of macrophages in the spleen and tails of affected cmo mice. (A) Western blots (WB) of whole-cell lysates of bone marrow–derived macrophages (BMM), mast cells (MC), and osteoclasts (OC) obtained from wt and cmo mice probed with an antibody against PSTPIP2. (B) Absence of PSTPIP2 in immunoprecipitates (IP) from cmo BMM. IgG indicates immunoglobulin G. (C) Sections of tails and spleens of cmo mice stained for the macrophage marker F4/80 (brown) and counterstained with hematoxylin (blue) showing extensive macrophage infiltration. (D) Development of splenomegaly in cmo mice more than 13 weeks old. Data ± SD, *P < .01, Student t test; n ≥ 10.