VGLL4 and heart failure: To corroborate these in vitro observations and to avoid heart failure-associated secondary effects, we decided to use a low-dose (0.33 × 1010 GC/g) AAV.VGLL4K225R to activate VGLL4 in the neonatal heart, so that VGLL4 regulation of CM maturational hypertrophic growth would not be confounded by heart failure that occurred in the high-dose AAV.VGLL4K225R transduced mouse pups [8].