CTSK and rheumatoid arthritis: All of examined genes, the regulator of cell growth and proliferation mTOR, the autophagy marker ULK1, the cyclin-dependent kinase inhibitor p21, the apoptosis indicator caspase-3, the proinflammatory cytokine TNFα, and the proteases MMP-9 and cathepsin K, were significantly upregulated at baseline in a sample of RA patients (n = 33) compared with healthy subjects (data not shown).