The α-SMA-positive layer surrounding the pulmonary artery was markedly thickened with a significantly higher number of Ki-67-positive cells in the CDH lungs without treatment than in the control lungs and those receiving ONO-1301SR treatment, which displayed a comparable number of α-SMA and Ki-67 double-positive cells (Fig 6E–6H). This evidence concerns the gene ACTA1 and congenital diaphragmatic hernia.