OGN and Arthritis: Many of the most significantly regulated genes identified by this microarray study have documented roles in the pathogenesis of OA, arthritis or bone formation including seven of the top 10 upregulated genes (POSTN, ASPN, COL6A3, COL3A1, OGN, DIO2, TNFSF11) and two of the top 10 downregulated genes (LEP, APOB) [20-27].