FIGURE 6.

Sam68 mediates HGF-induced migration through MAPK-directed phosphorylation sites in breast cancer cells. A, MDA-MB-231 cells expressing either control or Sam68 siRNA were assayed for HGF-induced migration. Inset, Western blots showing Sam68 knockdown and p38 loading control. B, MDA-MB-231 breast cancer cells were transiently transfected with 2.5 μg of vector or 1–2.5 μg of Myc-tagged WT- or m1-Sam68 and assayed in Boyden chambers for HGF induced migration. C, expression of Myc-tagged and endogenous Sam68 protein and ERK1/2 activation were detected using specific antibodies; total ERK1/2 served as a loading control. D, MDA-MB-231 cells transiently transfected with 2.5 μg of Myc-tagged WT-, m1-, and m4-Sam68 were subjected to HGF-induced Boyden chamber migration assays. Schematic representations of Myc-tagged WT- and m4-Sam68 are shown. Inset, transfected Sam68 protein levels were detected using Myc tag-specific antibodies. E, HaCaT cells were transiently transfected as in D and assayed for migration. * denotes significance (p < 0.05) relative to vehicle and between indicated groups, as determined by unpaired Student's t test. F, endogenous and Myc-tagged WT- and m4-Sam68 and total ERK5 were visualized by Western blotting using specific antibodies. Slower running (higher migrating) Sam68 bands indicate Myc-tagged proteins.