Figure 1.

Ricin-induced activation of cell signaling pathways and downstream formation of damage mediators. (1) The ribotoxic stress response characterized by MAP3K (PKR and ZAK) activation of MAPK (p38 and JNK) signaling; (2) The nuclear factor kappa B pathway, which is activated upon IкK-induced IкB phosphorylation and degradation; (3) NALP3 inflammasome-mediated IL-1β activation; (4) Apoptotic cell death attributed to pro-apoptotic caspase activation; (5) Proinflammatory cytokines and damage mediators released upon activation of the various signal transduction pathways activated by ricin.