In addition, expression of EMT markers, matrix metalloproteinases 2 and 9 was higher in lung tissues (harboring metastatic tumors) from mice bearing LLC cells with PD-L1 overexpression and lower in lung tissues from mice bearing LLC cells with PD-L1 knockdown (Fig. 4d–f and Fig. 4h–j). This evidence concerns the gene MMP2 and metastatic neoplasm.