For example, TFAP2A enhances the metastatic ability of lung adenocarcinoma through the miR-16/TFAP2A/PSG9/TGF-β axis [9] and promotes the progression of lung adenocarcinoma through epithelial–mesenchymal transition (EMT) by inducing the expression of KRT16 [10]. Here, PSG9 is linked to lung adenocarcinoma.