Although further experiments are necessary to determine the molecular mechanism by which the Ang II-mediated RAS pathway regulates Adra1a mRNA levels, our data showed that Ang II suppressed Adra1a mRNA levels under PAH conditions resulting in a decrease in ERK1/2 activity (Figs. 1F, 2C, and 5I). Here, MAPK3 is linked to pulmonary arterial hypertension.