FIGURE 1.

ERK1/2 activation is required for HGF-induced CD44v5 up-regulation and migration in keratinocyte cells. A, HaCaT cells were serum-starved for 18 h and pretreated with 10 μm of the MEK1/2 inhibitor U0126 for 30 min. Cells were then treated with either vehicle or 50 ng/ml HGF for 4 h. CD44v5 expression and ERK1/2 activation were determined with specific antibodies. Total ERK1/2 served as a loading control. B, Boyden chamber migration assays performed with HGF-stimulated HaCaT cells in the presence or absence of 10 μm U0126. MEK inhibitor was added to both upper and lower chambers (wells). C, Boyden chamber migration assays with HaCaT cells transiently transfected with control or CD44v5 siRNA. Inset, Western blots showing CD44v5 and ERK1/2 expression upon CD44v5 knockdown. Forty eight hours post-transfection, cells were harvested and assayed for HGF-induced migration. * denotes significance (p < 0.05) relative to vehicle between indicated groups, determined by unpaired Student's t test. § denotes no statistical difference relative to vehicle.