The extracellular signal-regulated kinase (ERK)1/2 and p38 mitogen-activated protein kinase (p38-MAPK) pathways are known to play a key role in cardiac fibroblast proliferation, and the dysregulation of these pathways has been linked to arrhythmias, myocardial infarction, hypertension, and heart failure. The gene discussed is MAPK14; the disease is Arrhythmia.