A. EATR assay. Chondrocytes were treated with FGF18 (50 ng/mL; 16 hours) and Actinomycin (1μg/mL; last 4 hours) where indicated. ER acidification was measured by FACS. Mean +/- standard error of the mean (sem) of N=17 (veh), N=17 (FGF18), N=5 (actinomycin), N=5 (actinomycin + FGF18) biological replicates. Analysis of variance one way (ANOVA) p<0.0001; Tukey's post hoc test ***p<0.0005; NS not significant. 