Except for the common ubiquitin ligase activity, SOCS1 and SOCS3 are capable of a direct inhibition on JAK kinase activity through a short motif called Kinase Inhibitory Region [18], which is however, unlikely true in NPC cells in that lacking of the direct interaction between SOCS1 and JAK. Here, SOCS3 is linked to nasopharyngeal carcinoma.