To demonstrate that inhibition of HDAC6 is accompanied by translocation of Bax to the mitochondria, serum-starved PAH-PASMCs treated or not with TubA or ACY-775 for 48 hours were subjected to immunofluorescence labeling for Bax and mitochondria were stained with MitoTracker Red. This evidence concerns the gene HDAC6 and pulmonary arterial hypertension.