Fig. 2. The total AXL protein degradation rate is extended in EGFR-TKI resistant cells.

The efficiency of siAXL was confirmed using real-time PCR and Western blotting (a). The effects of gefitinib or osimertinib on the cell viability were evaluated after cells were transfected with siNC or siAXL compared with control (no transfection) in HCC827-gef cells (b) and HCC827-osi cells (c). Cycloheximide (CHX) was treated to stop the protein production and the protein expression of AXL (140 kda) was detected by Western blotting over the indicated time points. The expressions of AXL and β-actin were quantified by densitometry using ImageJ. AXL expressions were normalized to β-actin and further compared with 0 h expressions (d). mRNA expression of AXL and GAS6 were detected by real-time PCR using β-actin as a reference gene (e). Data are presented as the mean fold changes ± SD of three independent experiments. *P < 0.05, **P < 0.01, ***P < 0.005 by t-test