Studies in a monocrotaline (MCT)‐induced PAH model revealed that monocrotaline pyrrole (MCTP), the main metabolite of MCT, targets the pulmonary arteries to induce transforming growth factor β (TGF‐β) expression via activating JAK/STAT signalling.36, 37 TGF‐β was also noted to induce interleukin 6 (IL‐6) production through the JAK/STAT signalling cascade.38 Together, these data support that JAK/STAT signalling is likely implicated in the pathogenesis of PAH. Here, IL6 is linked to pulmonary arterial hypertension.