MAPK3 and infection: To examine if the presence of the capsule, as one of the major virulence factors of Nm, has an effect on the infection rates upon inhibition of the Erk1/2 and p38 MAPK pathways, infection experiments were conducted with the capsule-deficient mutant strains of serogroups B and C (MC58siaD− and WUE2120siaD−, respectively).