Expression of RAB38 and RAB32 proteins in MKs and platelets. (A, left panel) Western blots of human, mouse, and rat total platelet (Plts) lysates (10 µg) showing expression of RAB38 in all 3 species but not of RAB32 in rat platelets. Actin was present as a loading control. Representative blots from 3 independent experiments. (A, right panel) Reverse transcription polymerase chain reaction amplification of mRNA from rat lung, spleen, and platelets and mouse platelets, indicating absence of RAB32 mRNA in rat platelets. Rat plts 1: OFA rat; rat plts 2: Wistar rat. (B) Confocal images of immunolabeled mouse MKs. Left panels show RAB32 or RAB38 labeling (green), 5-HT or VWF labeling (red), and the merged images. Right panels show for each labeling a line scan of the fluorescence intensity along the drawing line visualized in the merged images. Bar, 5 µm. Images are representative of at least 3 independent labeling experiments.