MEF2A and persistent truncus arteriosus: Importantly, all of these manifestations of the activation of the CaMKII-HDAC4-MEF2 hypertrophic pathway with TAC in NTL mice were also present in the GqI+/– and the GqI–/– mice, indicating that inhibition of cardiac Gq-coupled receptors has no effect on the activation of the CaMKII-HDAC4-MEF2 pathway with TAC.