In order to determine the mechanism leading to MDSC accumulation and consecutive hepatotoxicity in tumor bearing mice with liver damage (B16 and EL4) and without (RIL175 and CT26), we next screened tumor-conditioned media (Figure 4A) and serum (Figure 4B) of tumor-bearing animals for cytokines and chemokines that have been described to expand MDSC [19] including interleukin-6, CCL-2, GM-CSF, M-CSF, KC and VEGF. This evidence concerns the gene CSF2 and neoplasm.