SOX4 and SOX11 are expressed in mouse FLS. A, Levels of Sox4 and Sox11 RNAs measured by RT-qPCR and normalized for Gapdh RNA levels. B, Assay of SOXC proteins present in whole-synovium lysates from two wild-type mice (1 and 2). Western blots were hybridized with SOX4-specific and pan-SOXC antibodies. GAPDH detection is shown as loading control. The molecular weight of protein standards running close to the proteins of interest is indicated. C, In situ hybridization of adjacent knee sections from 6-week-old mice with Sox4, Sox11 and Prg4 RNA probes. Left panel, section stained with nuclear fast red. The box corresponds to the areas magnified in the other panels. Arrows and SL, synovial lining; SI, synovial intima; AC, articular cartilage. D, Flow cytometric phenotyping of mouse primary synovial cells at passage 4 with FITC-conjugated CD90.2 and APC-conjugated CD14 antibodies. E, Relative levels of Sox4 and Sox11 RNAs measured by RT-qPCR in similar cells as in panel D. F, SOX4 and SOX11 proteins detected in western blots of whole lysates from cells immunophenotyped in panel D.