Small-molecule Syk inhibitors, such as R406, have been shown to be protective in the treatment of immune-inflammatory diseases, including allergic rhinitis, rheumatoid arthritis, IgA nephropathy, and acute lung injury (Wenzel et al., 2009; Weinblatt et al., 2010; Wu et al., 2019; Kost-Alimova et al., 2020). Here, SYK is linked to rheumatoid arthritis.