STAT3 and cancer: This oncogenic potential has been associated with strains expressing cytolethal distending toxin (CDT), which can activate: (i) the JAK2 (Janus kinase 2)/STAT3 (signal transducer and activator of transcription 3)/MMP9 (matrix metalloproteinase-9) signaling axis implicated in tumor development [27,28] and (ii) glycogen synthase kinase 3 beta (GSK3b), a key regulator of cancer metastasis [29].