STAT3 and infection: The production of IL-6 and G-CSF leads to receptor-mediated activation of the JAK2/STAT3 (Janus Kinase/signal transducer and activator transcription) pathway [26,27], which subsequently leads to the induction of cell survival signals by producing increased levels of the anti-apoptotic proteins Bcl-2 and Bcl-XL. In case of C. diphtheriae, the knowledge about molecular signaling upon infection of macrophages is scarce.