Intracellular OPN has been implicated in many cellular processes and its expression is required for Toll-like receptor 9-dependent production of IFN-α.19 Two recent studies by Carbone et al. suggested OPN as a potential predictor of poor outcome in patients with severe carotid atherosclerosis20 and as a valuable biomarker in SLE, showing a strong association with subclinical atherosclerosis, measured as carotid intima-media thickness (IMT).21 In contrast, OPN plasma levels (pOPN) and early vascular markers of atherosclerosis in asymptomatic young Scandinavian adults were poorly correlated.22 This evidence concerns the gene SPP1 and atherosclerosis.