Figure 5.

A schematic model of negative regulation of the ERK pathway by MEK1 SUMOylation. The dynamic changes of MEK1-SUMOylation and—phosphorylation show a similar trend for membrane expressing HA (A) and virus infection (B), but the crossover point between treatments for virus infection appears 1 h later than when the membrane expresses HA. We propose a model that influenza virus activates the ERK pathway by negatively controlling MEK1 SUMOylation (C). HA of influenza virus is essential for regulation of vRNP export in the ERK pathway through down regulation of MEK1 SUMOylation, namely, HA triggers the switch from MEK1 SUMOylation to phosphorylation of the ERK pathway and facilitates its infection.