PMN can activate p38 mitogen-activated protein kinase (MAPK) in a HOCl-dependent manner via MPO [34], which promotes transdifferentiation of fibroblasts to myofibroblasts [18], key cellular drivers of interstitial collagen production and fibrosis after myocardial ischemia [31]. The gene discussed is MAPK14; the disease is myocardial ischemia.