Fig. 1

Highly brain metastatic lung cancer cells achieved prominent resistance to PEM. A PC9 and PC9-BrM3 cells were treated with different doses of PEM for 72 h and CCK-8 assays were performed to determine their viability. B Survival of PC9 and PC9-BrM3 cells after treatment with certain concentrations of PEM (0, 20, 40 nM) and the results of clonogenic assays showing the treatment effect. Pixel density quantification of clonogenic assays is shown as histogram. C Flow cytometry analysis of PC9 and PC9-BrM3 cells treated with PEM (20 nM) for 24 h. (n = 3, **p < 0.01, ***p < 0.001)