MAPK8 and enthesitis-related juvenile idiopathic arthritis: Notably, p-AKT, p-CBL, p-JNK, p-PLC-γ, p-STAT1, p-STAT3, p-STAT6 and p-ZAP70 mean fluorescent intensity (MFI) levels were significantly elevated in ERA patient PB subsets in all three cellular compartments.