NFKB1 and rheumatoid arthritis: Activation of the BTK–SYK axis culminates in PI3K, NF‐κB, and MAPK‐dependent downstream signaling cascades to regulate a variety of cellular processes, such as cell proliferation, differentiation, and cytoskeletal remodeling, exhibiting therapeutic potential in immunotherapy, such as rheumatoid arthritis (RA).161, 162