NRG1 and nasopharyngeal carcinoma: The inability of Nrg-1 in overcoming the proinflammatory inhibitory effects on NPC differentiation may reflect the robust effect of TNF-α on NPC differentiation and the fact that Nrg-1 was not able to reduce TNF-α expression in proinflammatory microglia to its basal level detected in resting microglia.