Fig. 4

Anti-PD-L1 antibody treatment inhibits turnover of mutant but not wild type EGFR. A Representative images and quantification of EGFR in BEAS-2B cells with EGF stimulation, N = 6. Paired student’s t-test at 60 and 90 min were calculated. B, C EGF-stimulated EGFR degradation in (B) BEAS-2B PD-L1 KO cells, N = 4, and C BEAS-2B cells treated with αPD-L1 antibody, N = 4. Rate constants are compared using extra sum-of-squares F test. D EGFR protein in WT, PD-L1 KO and PD-L1-reexpressing H1650 cells. One way ANOVA and post-hoc Tukey test. E EGFR protein expression in H1650 cells treated with reagent grade αPD-L1 antibody (clone # 130021, Novus Biologicals) and clinical Durvalumab as compared to isotype IgG control antibody. One-way ANOVA and post-hoc Tukey test. F EGFR protein in H1650 cells with anti-transferrin receptor antibody (aTfR) antibody treatment. One sample t-test. G EGFR protein expression in cell lines treated with αPD-L1 antibody. One sample t-test. H, I Quantification of EGFR degradation in H H1650, N = 3, and I BEAS-2B, N = 3, in the presence of cycloheximide. Rate constants are compared using extra sum-of-squares F test. For B–I Western blot quantifications of EGFR protein normalized to actin expression are shown. All error bars = SEM. * ≤ 0.05, ** ≤ 0.01, *** ≤ 0.001, # = 0.051