FSTL3 and pulmonary arterial hypertension: Finally, in light of the emergence of new PAH therapies, particularly in relation to Sotatercept—a fusion protein that traps activins and growth factors leading to reversal of vascular remodeling101—Guignabert et al found that elevated serum activin A and follistatin-like 3, key members of the activin pathway, predicted death or lung transplantation in patients with idiopathic, heritable, or anorexigenic-associated PAH, independent of other noninvasive parameters currently used for PAH risk assessment (New York Heart Association Functional Classification, 6MWD, and NT-proBNP).23