NRG1 and myocardial infarction: In addition, Shiraishi, Yamaguchi & Suzuki (2022) demonstrated that neuregulin 1 (Nrg1) produced by BMDM and Nrg1 co-receptor ErbB expression on the surface of cardiac fibroblasts increased after MI, which combined to activate the downstream PI3K/Akt pathway, inhibit the aging and apoptosis of cardiac fibroblasts, promote their proliferation and lead to fibrosis.