Figure 4

FAK and paxillin induce SCC migration via activation of the mitogen activated protein kinase ERK1. (A) Neomycin resistant control (neo), FAK overexpressing, and paxillin overexpressing (pax) clones were treated with the MEK inhibitor PD98059 (PD) or vehicle as described in Materials and Methods. Relative phosphorylated ERK1 and total ERK1 expression was determined by western blot using anti-phosphoERK1 (anti-pERK1) and anti-ERK1 antibodies. This experiment was repeated with additional independently isolated clones with similar results. Representative blots are shown. (B) Densitometric quantitation of blots in Fig. 4A. (C) FAK or paxillin (pax) overexpressing clones or neomycin resistant control cells (neo) were plated on plastic tissue culture dishes and treated with the MEK inhibitor PD98059 (PD) or vehicle as described in Materials and Methods. The number of cells which migrated into the blank area of the plate within 24 hours was counted. (D) FAK or paxillin (pax) overexpressing clones or neomycin resistant control cells (neo) were plated into Matrigel invasion chambers and treated with the MEK inhibitor PD98059 (PD) or vehicle. The number of cells which migrated through the reconstituted basement membrane were fixed, stained, and counted. These experiments were performed three times with similar results. Error bars indicate SEM.