library_construction_protocol: Total RNA was extracted from a single mouse joint (including cartilage surfaces and underlying subchondral bone). RNA was extracted using TRIzol reagent using manufacturer's protocol (Invitrogen) and tissues disrupted using Precellys steel beads; contaminating DNA was removed with TURBO DNAse kit (Ambion). Then, RNA was cleanued-uo with RNeasy Mini kit (Qiagen). Library was constructed using the massive analysis of cDNA ends (MACE) 3' mRNA-Seq; stranded, single end (1x75bp)