MAPK3 and infection: To explore whether the increase in phosphorylation of these proteins was related to autophagy, 3D4/21 cells were pretreated with PD98059, SP600125, and LY294002, the specific inhibitors of Erk1/2, JNK and Akt, respectively, for 1 h before infection by AH, and then the expression levels of autophagy-related proteins and the phosphorylation of Erk1/2, JNK and Akt were evaluated.