IL4 and pulmonary arterial hypertension: This data was corroborated by immunostaining of human lung tissue of patients with Schistosoma-induced PAH, which presented higher staining intensity for IL-13, IL-4Rα, phospho-signal transducer and activator of transcription factor 6 (pSTAT-6, a key target of IL-4 and IL-13), and periostin (another target of IL-4 and IL-13 signaling), which reinforces the clinical importance of these findings.