MAPK3 and infection: Our observation of a monophasic activation of ERK1/2 in the early phase of SARS-CoV-2 infection (Fig. 1; Fig. S1) adds to previous studies that already linked Raf/MEK/ERK signaling to the infection process of various viruses [15–23, 43, 44], including coronaviruses [27, 28, 45–47].