In this study, we will collect the pleural effusion from lung cancer patients. We will characterize the EGFR status of the cancer cell from malignant pleural effusion and try to establish the cancer cell lines from these patients. We hope to establish several cell lines with different mutations and then we can compare the difference responses and signal pathways in these cell lines. We can also explore the detailed mechanism of TKI responsive cancer cell and try to develop other agent to enhance the pathways.