Fig. 4. MK induces paxillin phosphorylation. UMR-106 cells were cultured for 8 hours in DMEM and stimulated with MK (0 ng ml^–1, 50 ng ml^–1, 200 ng ml^–1, 500 ng ml^–1 or 1000 ng ml^–1) in DMEM for 5 minutes (A) or 200 ng ml^–1 of MK for 0 minutes, 5 minutes, 10 minutes or 30 minutes (B). (C) Cells were incubated for 5 minutes without addition (C), with 200 ng ml^–1 MK (MK) or 200 ng ml^–1 MK plus 100 µg ml^–1 anti-₄-integrin antibody (anti-₄ + MK). Paxillin was immunoprecipitated from cell lysate and analysed by western blotting using anti-phosphotyrosine antibody (Anti-P-Tyr) or anti-paxillin antibody (anti-pax). Relative densitometric densities are shown below the bands obtained by western blotting. In (C), three experiments were performed and a typical result was shown; the increased phosphorylation by MK was suppressed by anti-₄-integrin antibody to 36% of the value without the antibody.