LYN and rheumatoid arthritis: Interestingly, similar to Lyn-deficient mice, R131H-FcγRIIATg mice develop spontaneously autoimmunity at old age, with a complex spectrum of symptoms similar to those found in human rheumatoid arthritis (erosive pannus) and SLE (antinuclear antibodies, glomerulonephritis with immune complex deposition in the renal basement membrane, pneumonitis and non-erosive arthritis)42.