CTSB and rheumatoid arthritis: The PDGF is known to play a crucial role in proliferation and migration, cause an increase in mRNA and protein expressions of proinflammatory cytokines such as interleukin-1b and interleukin-8 by synergizing with the tumor necrosis factor in the RA-fibroblast-like synoviocytes (FLS), increased the amounts of FLS in the G2/M cell cycle phase, promote morphological changes of the FLS cells to a dendritic shape, and cause a significant increase in cathepsin B secretion that can degrade some collagen types and proteoglycans in acidic physiological conditions [14, 16, 20, 21, 25–32].