FIGURE 1.

Human MKs express and synthesize DDR1 tyrosine kinase. A, total cellular RNA was extracted from MKs and fibroblasts (Fb) as positive control. β2-microglobulin was used as housekeeping gene. NTC indicates “no template” controls in the reverse transcriptase and PCR steps. RT-PCR products were loaded in duplicates for each cell type. B, MK and fibroblast lysates were subjected to Western blot analysis using an anti-DDR1 antibody. The anti-DDR1 blocking peptide (B.P.) was used to confirm the specificity of the antibody. Actin was probed to show equal loading. C, DDR1 expression was demonstrated in peripheral blood platelet lysate (Plt) by Western blot. Shown here are representative Western blots out of three independent experiments. D, MKs were cytospun on polylysine-coated glass coverslips, fixed, and stained with an anti-DDR1 antibody (red) and an anti-CD61 antibody (green). The graphs report the intensity of the fluorescence signal along the x axis for each fluorochrome on the optical section. (Immunofluorescence staining, DM IRBE inverted microscope, magnification 40×.) Scale bars are 25 μm. Nuclei were counterstained with Hoechst 33288 (blue).