HES5 and pulmonary arterial hypertension: Elevated Notch3, TMIC fragment, and Hes5 expression in PAH versus non-PAH PASMCs demonstrated an increased Notch3 signaling, recapitulating findings in our R169C mice and other PH models.9,46 Upregulation of BiP and ROS generation in PAH PASMCs were also similar to observations in hypoxia-treated TgNotch3R169C mice.