Immunohistochemistry of BM stained with phosphospecific anti-AKT antibody.

(A) Myeloma marrow with immunostained plasma cells in a membrane-specific pattern. (B) Myeloma marrow stained with antibody after antibody was first preabsorbed with phosphorylated AKT peptide. (C) Myeloma marrow (same as used in panel B) stained with the same antibody after antibody was preabsorbed with nonphosphorylated AKT peptide. (D) MGUS marrow stained with phosphospecific AKT antibody. Three plasma cells are shown with arrows; original magnification × 400. (E) Frequency (mean ± SD) of plasma cells immunostaining in patient marrows.