MAPK8 and rheumatoid arthritis: Studies reported that aberrant activation of Hedgehog pathway in RA patients contributed to RA-FLS multiplication and migration in a tumor-like behavior leading to synovial inflammation, joint destruction, and pannus formation through different mechanisms including activation of MAPK/Jun N-terminal kinase pathway, MAPK/extracellular signal-regulated kinase pathway, and upregulation of MMP1 and MMP3 which plays a crucial role in FLS aggressive behavior (Zhu et al. 2020c; Mousavi et al. 2021).