Figure 6.

Schematic diagram showing steps in the signaling pathway by which P. aeruginosa up-regulates human MUC2 mucin gene transcription. As indicated, P. aeruginosa releases LPS, thereby activating a c-Src-Ras-Raf-1-MEK1/2-MAPK (ERK1/2)-pp90rsk pathway, which in turn leads to the activation of NF-κB and triggers MUC2 mucin transcription. LBP, LPS-binding protein. The overproduced mucin, in concert with abnormal airway lining fluid secondary to CFTR mutation, leads to airway mucus obstruction and lung failure.