NOS2 and rheumatoid arthritis: EPC- endothelial precursor cells, PKC- protein kinase C, VEGF- vascular endothelial growth factor, NADPH oxidase- nicotinamide adenine dinucleotide phosphate, PPAR-gamma- peroxisome proliferator-activated receptors, MAPK- mitogen-activated protein kinase, DM- diabetes mellitus, RCT- randomized control trial, iNOS- inducible nitric oxide synthase, ICAM 1- intercellular adhesion molecule 1, VCAM 1- vascular cell adhesion protein 1, PWV- pulse wave velocity, AI- augmentation index, CAD- coronary artery disease, PIO- pioglitazone, RA- rheumatoid arthritis