D. Co-immunofluorescence of p-IRS1 (S307 mouse) and TFEB in IRS1-overexpressing RCS chondrocytes treated with FGF18 (50 ng/mL) for 12h. Nuclei (N) were stained with DAPI (blue) and delimited with dashed line. Scale bar 15 μm. Quantification of TFEB nuclear localization in IRS1-overexpressing vs non-expressing RCS. Mean +/- standard error of the mean (sem) of N=3 biological replicates. n= 124 cells analyzed; Student's un-paired T-test *p<0.05. 