Figure 4

Lymphatic-secreted HS activates tumor-cell migration signaling pathways in trans. A. Serum-free basal endothelial growth medium or conditioned medium (CM) harvested from hLEC treated as indicated was applied to cultured LLC for 10 min. The LLC were lysed and the indicated target proteins were detected by Western immunoblotting. A representative gel image (top) as well as normalized densitometric quantification (below) from three independent experiments is shown. Relative protein expression was calculated as the densitometric ratio of phosphorylated protein to that of corresponding total protein, and normalized to the basal value. *P < 0.05, as compared to LLC treated with CM from control hLEC (CM-siDS). B. In separate experiments, the effects of blocking CCL21 (siDS + αCCL21) or treatments that alter HS biosynthesis (siNdst1 or siXylT2) on CM-mediated Erk1/2 phosphorylation were examined.