Fig. 2: PLK1 overexpression is associated with chemotherapy resistance.

A Correlation analysis between PLK1 expression status and overall survival rate in NSCLC patients receiving drug therapy. B Correlation analysis between PLK1 expression status and overall survival rate in NSCLC patients receiving radiation therapy. C–F Protein immunoblotting assay to detect PLK1 expression levels in drug-sensitive and drug-resistant cell lines, respectively: C HCC-827 and HCC-827/GR, D A549 and A549/DDP, E HCC-827 and NCI-H1975, F MIAPACA-2 and MIAPACA-2/MR. Each has the expression of GAPDH as the internal control. Protein expression was quantified by densitometry analysis using ImageJ and normalized against GAPDH expression. Data are presented as the mean ± SD. ***p < 0.001.