For instance, interferon gamma (IFN-γ) is secreted by Th1 (CD4+) cells, and the inverse correlation between IFN-γ and IK1/Kir2.1 expression was found in the rat heart with myocardial infarction, where Th1 cells responded to the stimulation by elevating the level of IFN-γ; the regulatory role of CD4 cells on IK1/Kir2.1 expression was therefore ascribed to IFN-γ (Li et al., 2016). This evidence concerns the gene CD4 and myocardial infarction.