MEF2A and persistent truncus arteriosus: Remarkably, Piezo1 KO mice failed to exhibit any evidence of activation of the CaMKII-HDAC4-MEF2 hypertrophic signaling pathway 2 d after TAC: the findings in Piezo1 KO mice 2 d after TAC were indistinguishable from those in their sham-operated controls (Fig. 4).