MYLK and pulmonary arterial hypertension: There are multiple pathways for the activation of myosin light chain phosphorylation including p21 activated kinase (PAK, [9], myosin light chain kinase (MLCK, [10]), and Rho-dependent kinase (ROCK) [11] and drugs that inhibit disregulated contractility are being investigated as potential therapeutics for pulmonary hypertension [12].