CD148 is expressed in human and mouse platelets. (A) Human platelets. (Ai) Resting and (Aii) thrombin-activated (1 U/mL) human platelets were stained with a mouse anti–human CD148 primary antibody (CD148, gray line) that recognizes the extracellular region of CD148, or the same amount of an isotype control antibody (IgG, black line), followed by a FITC-conjugated anti–mouse IgG secondary antibody and analyzed by flow cytometry. No detectable change in CD148 surface expression was observed in thrombin-activated platelets. (B) Mouse platelets. (Bi) Resting wild-type (WT) mouse platelets were incubated with either hamster anti–mouse CD148 primary antibody (CD148, gray line) that recognizes the extracellular region of mouse CD148, or an isotype control antibody (IgG, black line). Platelets were subsequently stained with FITC-conjugated anti–hamster secondary antibody and analyzed by flow cytometry. (Bii) Whole-cell lysates (WCLs) prepared of WT and CD148 transmembrane-knockout (KO) mouse platelets were Western blotted for CD148. A 220-kDa band was detected in the WT sample but not in the KO sample.