Establishment of stable or drug resistant cell lines

Lentivirus production and infection for RSK2, GDH1, or CREB knockdown in human cancer cell lines were performed as previously described.³⁰ Cells were transduced with retroviral vectors harboring GDH1 WT or Y135F followed by 300 mg/mL hygromycin selection for stable expression, and GFP-luciferase genes for bioluminescent imaging. HCC827 and PC9 erlotinib or osimertinibresistant cell lines were generated by culturing parental cells with escalating doses of erlotinib or osimertinib. The resistant cell lines were maintained in 1 μM of erlotinib or osimertinib, which were removed from the media for 1 day before conducting experiments.