To determine whether loss of miR‐574 causes dysregulation of MEG and NEMG expression for the ETC complexes and compromises ETC activity in vivo, we first quantitatively measured their protein expression levels and found that FAM210A and MEG protein expression was significantly induced in miR‐574 KO hearts compared to WT hearts at 3 days after TAC surgery (Figs 8J and Fig EV5A and B). This evidence concerns the gene MIMS1 and persistent truncus arteriosus.