COL1A1 and pulmonary arterial hypertension: In this study, we demonstrated that knockout of ccdc80 in zebrafish caused dilation of the ventral artery and decreased the expression of both edn1 and col1a1. We also showed that Ccdc80 immunoreactivity was increased in the hypertrophied media and adventitia of the pre-acinar PAs and in the thickened intima, media, and adventitia of the obstructed intra-acinar PAs in a rat PAH model.