There is a body of evidence that NO formation could be implicated in mediating silica induced pulmonary fibrosis. As a reactive free radical, NO may not only contribute to lung parenchymal tissue injury but also has the ability to combine with superoxide and form a highly reactive toxic species peroxynitrite, which can induce extensive cellular toxicity via a variety of mechanisms in the lung tissues. Several cytokine is required for NO production. NF κB plays a particularly important role in the regulat...