The upstream signaling components EPAC1 RAPGEF3, RAPGEF6, EPAC2 RAPGEF4, and RAPGEF5 were not transcribed in MSCs from mild or severe COVID-19 patients (data not shown).The AKT is a central molecule that triggers other branches of intracellular signaling pathways, including the β-catenin via, which is probably active in vivo in MSCs comparing our data of severe over mild cases. The gene discussed is RAPGEF4; the disease is COVID-19.