DGKζ deficiency enhances surface expression of GPVI without increased messenger RNA (mRNA) in murine megakaryocytes. (A) Bone marrow–derived hematopoietic stem cells from WT and DGKζ-KO mice were cultured in TPO plus SCF for 0, 1, 5, or 8 days to obtain megakaryocytes, and surface expression of GPVI, integrin α2, integrin αIIb, and GPIbα was measured by flow cytometry. Mean fluorescence intensity (MFI) is reported as the mean ± SEM (n = 6). (B) Mature megakaryocytes were enriched by using a BSA density gradient, and RNA was extracted. Quantitative RT-PCR was performed, and relative expression levels of GPVI, FcRγ chain, integrin α2, integrin αIIb, GPIbα, and DGKζ in DGKζ-KO megakaryocytes are shown relative to WT expression levels (n = 5). Hypoxanthine-guanine phosphoribosyltransferase was used for normalization. *P < .05, **P < .01 of DGKζ-KO as compared with WT megakaryocytes. N.D., not detectable.