D. Lamp1 immunofluorescence (red) in RCS chondrocytes treated with vehicle (5% ABS) and FGF18 (50 ng/mL) for 16 hours. Insets show magnification of the boxed area. Nuclei were stained with DAPI (blue). Scale bar 15 μm and 2 μm (higher magnification boxes) . Bar graph shows quantification of Lamp1-positive vesicles/cell. Mean +/- standard error of the mean (sem) of N=3 biological replicates/treatment. n=45 cells were analyzed. Student paired T-Test *p<0.05. 