NR3C2 and persistent truncus arteriosus: In response to TAC, both EC‐MR+/+ and EC‐MR−/− LV showed an isoform switch from adult to fetal myosin heavy chain (MHCα to MHCβ) that resulted in an increased MHCβ/α ratio in TAC mice relative to Sham controls, in which the switch to MHCβ did not occur (Fig. 2D).