TNNI3 and heart failure: 30), but our study emphasizes the importance of changes in the monophosphorylated state of cTnI (17, 23). Fig. 5 shows that monophosphorylation can occur in cells with sufficiently active PKD; this may occur during α-adrenoreceptor stimulation in heart failure when the β-adrenoreceptor pathway is down-regulated (21, 31).