IL6 and neoplasm: When the tumor tissues were stained with the antibody of the proliferation marker Ki67, a lower number of Ki67 positively-stained cells were detected in A549IL-6si cell-derived tumors (Fig. 1D, lower panel), which is consistent with the tumor growth data (quantification of IL-6 and Ki67 staining results are shown to the right of Fig. 1D).