DUSP10 and persistent truncus arteriosus: Given that MKPs inactivate the MAPKs through direct dephosphorylation (21), we assessed whether MKP-5 regulates MAPK activity in the mouse left ventricle by measuring the phosphorylation of the MAPKs in cardiac tissues of Mkp-5+/+ and Mkp-5-/- mice after either sham or TAC surgery.