Figure 4.

CXCL12/CXCR4 signaling induces ERK1/2 expression and activation. 16HBE cells were incubated with 200 ng/ml CXCL12 as the indicated time and then subjected to Western blot analysis of ERK1/2 expression and activation. A. CXCL12 potently increased total ERK1/2 protein levels and pERK1/2 levels. The results are a representative of 3 independent experiments conducted. B. Blockade of ERK1/2 signaling by PD98059 abolished the stimulatory effect of CXCL12 on epithelial MMP-9 expression. 16HBE cells were pretreated with PD98059 (50 μM) for 30 min before CXCL12 stimulation. Addition of PD98059 completely diminished CXCL12 induced MMP-9 expression in 16HBE cells.