Some cytokines seem to be good indicators of PAH progression like the monocyte chemoattractant protein-1 (MCP-1), which is upregulated in early stage of PAH [123] or like IL-6, IL-8, IL-10, and IL-12 that increase with PAH severity and appear to be markers of poor survival rate [121]. The gene discussed is IL6; the disease is pulmonary arterial hypertension.