METTL3 and pulmonary arterial hypertension: The expression of FTO, ALKBH5, METTL3 and YTHDF1 were determined by quantifying overlap between the red and green signals, which revealed a faint fluorescence intensity for FTO and strong fluorescence intensity for YTHDF1 in small pulmonary arteries of MCT-PAH rats lung tissue, while no significant differences for ALKBH5 and METTL3 were found in the pulmonary vessels (Figures 5, 6).