TIMP1 and rheumatoid arthritis: In vivo, compared with the control group, the expression of PI3K, p‐AKT, IL‐1β, IL‐6, TNF‐α, MMP1, MMP3, and MMP9 significantly increased and the expression of TIMP1 decreased in the model group, indicating that the PI3K/AKT pathway is involved in RA, and controls the balance between MMPS and TIMP.