CTTN and acute respiratory distress syndrome: Although there are >100 known actin-binding proteins, two critical lung cytoskeletal effector proteins, encoded by recognized ARDS candidate genes, are central to lung EC barrier regulation: the multifunctional Ca2+/calmodulin-dependent nonmuscle myosin light chain kinase isoform (nmMLCK) and its cytoskeletal-binding partner, cortactin.