MYH14 and pulmonary arterial hypertension: [Ca2+]i can cause PASMCs contraction by allowing actin to activate the myosin ATPase in a Ca2+ -calmodulin (CaM) -myosin light chain kinase (MLCK) -myosin regulatory light chain (RLC) pathway and promote PASMCs proliferation and migration by stimulating transcription factors (TFs), which constitute the important foundation of PAH primely [27–29].