MAPK1 and viral infectious disease: Looking at the level of ERK phosphorylation in the Caco-2 mock control, the MEK activity was already at a level that was reached in Calu-3 cells only after virus infection (ratio pERK/ERK Caco-2 IAV-PR8 mock: 0.55, Calu-3 IAV PR8 solvent ctrl: 0.45, Caco-2 SARS-CoV-2 mock: 0.81, Calu-3 SARS-CoV-2 solvent ctrl: 0.7) (Figure 6 and Table 1).