PRTN3 and arthritic joint disease: BALB/c SKG mice were chosen to modelRA in these studies as the mice develop inflammatory polyarthritischaracterized by rheumatoid factor (RF), anticitrullinated proteinantibodies (ACPA) and symmetric affection of small joints., SKG arthritis is driven by arthritogenic T cells which can be synchronizedby intraperitoneal (i.p.)injection of mannan, a fungal polysaccharide.In all SKG experiments, arthritis was synchronized by mannan injectionon day 0.