TGFB1 and rheumatoid arthritis: A significantincrease in the level of TGF-β was found in animal models of RA(collagen-induced arthritis in mice and rats immunized with type 2 collagen, aswell as TNF-α transgenic mice) compared to non-immunized control animals.Moreover, the increase in the level of this cytokine was accompanied by theinvolvement and incorrect differentiation of mesenchymal stem cells andpre-osteoblasts in the subchondral area of the bone marrow, which contributedto joint degeneration.