TLR4 and nasopharyngeal carcinoma: The upregulated EGFR activated the PI3K/AKT pathway, thereby upregulating ROS production-suppressing genes, including farnesoid X receptor gene and toll-like receptor-4 gene, and downregulating ROS production-promoting genes, including matrix metalloproteinase 2 gene and transforming growth factor β1 gene, to decrease ROS production in the poorly metastatic NPC cells, which transformed the poorly metastatic NPC cells into highly metastatic cells after treatment with H-exos.