In this study, we applied microarrays to analyze gene expression patterns in a larger cohort of IPF lungs (13 IPF samples and 11 controls), and we analyzed the direct effects of osteopontin on human lung fibroblasts, alveolar epithelial cell migration and proliferation, and matrix metalloprotease (MMP) gene expression in vitro. Here, SPP1 is linked to idiopathic pulmonary fibrosis.