Here, we found that decreased expression of sarcoplasmic/endoplasmic reticulum Ca2+ ATPase 2a (SERCA2a) in the lung samples of PAH patients was associated with the down-regulation of bone morphogenetic protein receptor type 2 (BMPR2) and the activation of signal transducer and activator of transcription 3 (STAT3). The gene discussed is STAT3; the disease is pulmonary arterial hypertension.