STAT3 and cancer: Accumulating evidence has shown that CaMKII plays a critical role in the survival, proliferation, invasion, and differentiation of various cancer cells by activating multiple signaling pathways, such as the extracellular signal-regulated kinase (ERK), protein kinase B (AKT), the signal transducer and activator of transcription 3 (STAT3), and Wnt/β-catenin signaling pathways [15,16,17].