MMP9 and idiopathic pulmonary fibrosis: Further differential analysis revealed 23 commonly up-regulated (e.g., TNC, PLOD1, FKBP10, P4HA1, COL5A1 and VCAN) and 18 down-regulated (e.g., ANXA3, COL6A6, PRX and MMP9) DE proteins when comparing fibroblast foci versus IPF alveoli (Supplementary Figure S4H).