It has been demonstrated that mice lacking the fractalkine receptor, C-X3-C Motif Chemokine Receptor 1 (CX3CR1), highly expressed on microglial cells, showed an increase in the number of apoptotic neurons in layer V of the cerebral cortex (39); this effect can be related to the activity of insulin-like growth factor 1 (IGF-1) a trophic factor implicated in NPC survival which is reduced in CX3CR1-deficient mice (40, 41). This evidence concerns the gene IGF1 and nasopharyngeal carcinoma.