Increased content of BMP4 in the hearts of Tgαq*44 compared to WT mice both in control and in trained animals (Figure 4a), observed in this study, might be a consequence of the chronic renin–angiotensin–aldosterone (RAA) system activation, which is one of the most important mechanism of the heart failure progression (Hartupee & Mann, 2017). Here, REN is linked to heart failure.