IL6 and neoplasm: After IL-6 knockdown, CD11b+Gr-1− MDSCs decreased significantly in both the tumor tissues (26.90 ± 4.81 vs. 45.03 ± 4.84 vs. 44.67 ± 3.34%, P = 0.0039, P = 0.0057) and spleens (4.48 ± 0.47 vs. 7.53 ± 0.55 vs. 7.67 ± 0.61%, P = 0.0142, P = 0.0208) of the 4T1IL-6low group when compared with that of the 4T1WT and 4T1NC groups.