FIGURE 6.

PMP-bound Gas6 activates Axl better than free Gas6. HAECs were stimulated with PMPs alone or PMPs together with Gas6 for 15 min, after which cells were lysed. Axl phosphorylation was measured by Western blot in samples after immunoprecipitation (IP) with Axl-specific antibodies. Total Axl in immunoprecipitated samples served as loading control (A). The level of Akt (B) and ERK (C) phosphorylation upon stimulation with PMPs in the presence or absence of Gas6 was measured in cell lysates. Cells were treated with an Axl kinase inhibitor (R428) for 15 min prior to and during uptake of fluorescent PMPs. The level of uptake was measured by flow cytometry (D). Data show the mean and S.D. of three separate experiments. ns, not significant; **, p < 0.01; ***, p < 0.001; ****, p < 0.0001.