In 2011, to analyze the aberrantly expressed phosphorylated proteins in relapsed NPC, proteins from relapsed NPC and primary NPC tissues were subjected to protein array analysis, and KIT, ATP1A1, Synapsin, SEK1 and histone H2AX were up-regulated in relapsed NPC, while c-Jun was down-regulated [145]. Here, MAP2K4 is linked to nasopharyngeal carcinoma.