2012). Here, we report a significant reduction in the cardiac expression of microRNA-21's target gene Spry1 in vehicle-treated MI rats, and in IS-treated cardiac fibroblast cells. In vivo silencing of microRNA-21 in a pressure-overload model reduced cardiac ERK-MAP kinase activity, inhibited interstitial fibrosis and attenuated cardiac dysfunction (Thum et al. 2008). Here, SPRY1 is linked to myocardial infarction.