SPP1 and pemphigus foliaceus: In this study, we found that FGG was a hub protein in the protein-protein network interacting with IL6, FGA, FGB, CDH2, CPB2, SPP1, TGFβ3, and SERPIND1 that was significantly downregulated in both IPF and SSc-PF lung tissues (Figure 3), in agreement with recent work by Vukmirovic et al. (78).