To investigate the influence of culture method on drug response, HCC827 EGFR-mutant lung adenocarcinoma cells were cultured as a monolayer (2D) or hanging drop spheroid (3D) for four days (Fig. 1a) and subsequently challenged with EGFR tyrosine kinase inhibitors (TKIs) erlotinib or gefitinib for 72 h. This evidence concerns the gene EGFR and lung adenocarcinoma.