FIGURE 3.

DDR1-dependent regulation of MK migration. A, MKs were plated on type I collagen (Col I)-coated coverslips, in the presence of the DDR1-Fc blocking molecule or an IgG as control. Where indicated, MKs were pretreated with FcR blocking solution. After 16 h, adherent MKs were fixed, stained with anti-CD61 antibody, and then counted by fluorescence microscopy. B, MKs were left to migrate in a Transwell plate, upon coating the Transwell filter with type I collagen mixed with the DDR1-Fc blocking molecule or an IgG as control. Where indicated, MKs were pretreated with FcR blocking solution. After 16 h, MKs that had passed in the lower chamber were collected and counted by phase contrast microscopy. C, MKs adhering on the lower side of the Transwell filter were fixed and stained with anti-CD61 antibody and then counted by fluorescence microscopy. D, representative images of MK invasion of type I collagen. Cells adhering to the lower side of the Transwell coated filter, were fixed and stained with anti-CD61 antibody (red) antibody. (Immunofluorescence staining, Olympus BX51 microscope, magnifications 20×.) Scale bars are 100 μm. Nuclei were stained with Hoechst 33288 (blue). Reported results are the means ± S.D. (n = 6 independent experiments). **, p < 0.01.