IRAK4 and rheumatoid arthritis: Pharmaceutical companies are vigorously developing potent and safe IRAK4 inhibitors for the treatment of various clinical conditions, including RA [22,45], systemic lupus erythematosus (SLE) [46,47], inflammatory dermatitis [45], the activated B-cell-like (ABC) subtype of diffuse large B-cell lymphoma (DLBCL) [45], and marginal zone lymphomas (MZL) [48].