KL and pulmonary arterial hypertension: We then focus on emerging evidence that Kla is a nodal regulator across major cardiovascular pathologies-including atherosclerosis, myocardial infarction and ischemia/reperfusion injury, heart failure, valvular and arterial calcification, and pulmonary hypertension-where it can act as a context-dependent "accelerator" or "brake" of disease progression.