To evaluate the expression and phosphorylation levels of PLK1 in normal lung cells and primary and metastatic NSCLC, we observed the protein levels of PLK1 and its active form (phosphorylated at T210) by immunoblotting in normal lung fibroblast MRC5 cells, primary NSCLC A549 cells, and metastatic NSCLC (NCI-H460, NCI-H1299, and NCI-H358) cells (Fig. 1c). Here, PLK1 is linked to non-small cell lung carcinoma.