Additionally, mRNA expression levels of CTGF, DDR2, FGFR2, MYH10, and YAP1 genes were analyzed by quantitative polymerase chain reaction (qPCR) and found to be higher in the PAH group than in the control group (Figure 7d), which was consistent with the previous analysis. The gene discussed is DDR2; the disease is pulmonary arterial hypertension.