HIF1A and rheumatoid arthritis: Hypoxia can activate HIF-1α, regulate downstream p38/MAPK, PI3K/AKT, and other signaling pathways, affect DCs’ maturation and apoptosis, migration ability, glucose metabolism, antigen presentation ability, promote infiltration in synovial fluid and synovial tissue, aggravate immune response, and promote the continuous activity and pathological progress of RA (94, 95).