Consistently, the phosphorylation of signal transducer and activator of transcription 3 (STAT3), which is induced by the activation of IL-6 receptor/gp130 complex, is broadly detectable in various cell types, most remarkably in dermal microvascular endothelial cells, of SSc lesional skin irrespective of disease subtypes and disease duration, while totally absent or marginal in any cell types of healthy control skin [12]. Here, STAT3 is linked to systemic sclerosis.