Mittmann and colleagues [214] observed increased RGS4 mRNA but no change in RGS2 or RGS3 in such hearts, whereas Owen et al. [215] found the upregulation of RGS3 and RGS4 protein and mRNA in human heart failure, and Takeishi and colleagues [216] identified an apparent decrease in RGS2 protein. Here, RGS4 is linked to heart failure.