PDCD4 and ischemia: According to recent studies, miRs regulate cells or tissues exposed to myocardial infarction or ischemia, with reports finding that miR-21 protects hearts from ischemic injury via PDCD4 expression [2], miR-361 transfected into rat hearts causes mitochondrial fission and myocardial ischemic injury [36], and miR-30b protects cardiomyocytes by inhibiting cyclophilin D [3].