CCL2 and neoplasm: ELISA analyses of human sera from 50 cases with NPC and their non-tumor counterparts showed that the mean serum CCL2 concentration of NPC patients (342.3 ± 238.3 pg/ml, range 106.2 pg/ml-1448.6 pg/ml) was significantly higher than the mean serum CCL2 concentration of non-tumor patients (20.0 ± 7.0 pg/ml, range 15.0 pg/ml-45.3 pg/ml), (P < 0.05, Figure 1C).