SPP1 and idiopathic pulmonary fibrosis: We integrated four expression profiles, including 87 IPF samples and 40 normal samples and successfully found 11 key candidate genes (ANXA3, STX11, THBS2, MMP1, MMP9, MMP7, MMP10, SPP1, COL1A1, ITGB8, IGF1) related to the pathogenesis of IPF.