GAPDH and heart failure: Consistent with the normal echocardiographic and histological appearances of hearts at P15, transcriptional analysis of myocardium for a panel of heart failure markers, i.e. actin alpha 1 (Acta1), myosin heavy chain beta (Myh7), and natriuretic peptides A and B (Nppa and Nppb, respectively) (Fig. S2A-D) normalised to Gapdh (e.g. Fig. S2E), showed no clear indication of cardiac dysfunction.