Fig. 1

Accumulation of cholesterol in lipid rafts is responsible for EGFR-TKIs resistance. a, b PC-9 cells were exposed to gefitinib or osimertinib for 12 weeks to establish the gefitinib-resistant PC-9/GR and osimertinib-resistant PC-9/OR cells. c, d MTT assay was conducted to detect cell viability of NSCLC cells treated with gefitinib or osimertinib. e, f An Amplex® Red Cholesterol Assay Kit (A12216, Invitrogen, Carlsbad, CA, USA) was used to determine cholesterol level in the cytoplasm or lipid rafts of NSCLC cells. g Cells were incubated with 0.5 mg/mL Filipin (MB1848, Meilunbio, Dalian, China) for 2 h. Confocal images showed the free cholesterol in blue and the fluorescence intensity was analyzed. h-m Primary tumor gross appearance, i growth curves, j body weight, and k tumor weight of the tumor xenograft. l Cholesterol level in tumor tissues was determined. m IHC staining detected Ki67 expression in the indicated tumors. Data are expressed as mean ± SEM (n = 3) *p < 0.05, **p < 0.01, ***p < 0.001 in c, d, e, f, g and l. Data are expressed as mean ± SEM (n = 5) *p < 0.05, **p < 0.01, ***p < 0.001 in k