MAPK1 and infection: In contrast to the mock-treated cell lysate results, CHN06 infection led to a rapid and transient increase in ERK phosphorylation within 15 min p.i., which declined by 30 min p.i. and returned to the basal level by 2 h p.i. ERK phosphorylation increased again at 6 h p.i., subsiding by 12.5 h p.i. and then activation resumed between 108 h and 132 h p.i. (Fig. 3a).