SQSTM1 and pulmonary arterial hypertension: Given that Nrf2 is a critical regulator of the P62-Keap1-Nrf2 pathway, and to determine whether PAH induces oxidative stress while activating the P62-Keap1-Nrf2 pathway, we first employed immunofluorescence to examine the subcellular localization of Nrf2 following PAH treatment.