MAP2K6 and rheumatoid arthritis: To confirm the differential gene expression detected by the microarray analysis and pathway analysis, we sampled six genes (Sost, Lrp6, Tcf7l2, Alpl, Map2k6, and Nfatc4) involved in the significant signaling pathway “role of osteoblasts, osteoclasts, and chondrocytes in rheumatoid arthritis” for verification using real-time PCR.