In identified DEGs, we found two high degree gene in both PPI and TF-target gene networks, which were fos proto-oncogene, AP-1 transcription factor subunit (FOS) and one of top 10 up-regulated gene cathepsin K (CTSK) was involved in osteoclast differentiation and rheumatoid arthritis. The gene discussed is CTSK; the disease is rheumatoid arthritis.