Rhein inhibited invasion and migration in human nasopharyngeal carcinoma (NPC) cells through downregulation of the expression of MMP-9, vascular endothelial growth factor (VEGF), growth factor receptor bound protein 2, son of sevenless-1 and Ras, inhibition of the phosphorylation of ERK, p38 MAPK, and activation of transcription factor NF-κB [6]. Here, MMP9 is linked to nasopharyngeal carcinoma.