In another study by Frump et al., chemical chaperones Tauroursodeoxycholic acid (TUDCA) and 4-PBA have also proven successful in partially restoring cell surface expression of mutant BMPR2 in HPAH patient-derived lymphocytes and in pulmonary endothelial cells (PECs) from HPAH mouse model (Frump et al., 2013). The gene discussed is BMPR2; the disease is heritable pulmonary arterial hypertension.