Apoptosis; Fibroblasts/enzymology; Lung/enzymology; Pulmonary Fibrosis/enzymology; Receptor Protein-Tyrosine Kinases/metabolism; Receptors, Mitogen/metabolism; Actins/analysis; Actins/metabolism; Active Transport, Cell Nucleus/drug effects; Antibodies/pharmacology; Apoptosis/drug effects; Cell Survival; Collagen/pharmacology; Discoidin Domain Receptors; Fas Ligand Protein; Fibroblasts/drug effects; Fibroblasts/pathology; Humans; Immunohistochemistry; Lung/pathology; Membrane Glycoproteins/antagonists & inhibitors; Membrane Glycoproteins/pharmacology; Muscle, Smooth/metabolism; NF-kappa B/antagonists & inhibitors; NF-kappa B/metabolism; Pulmonary Fibrosis/genetics; Pulmonary Fibrosis/pathology; RNA, Small Interfering/pharmacology; Receptor Protein-Tyrosine Kinases/analysis; Receptor Protein-Tyrosine Kinases/genetics; Receptors, Mitogen/analysis; Receptors, Mitogen/genetics; Signal Transduction; Tumor Necrosis Factor Inhibitors; Tumor Necrosis Factors/pharmacology