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 The gene discussed is SPP1; the disease is systemic lupus erythematosus.