TEK and neoplasm: One of the EC markers expressed in both Kupffer-ECs and macrophage-ECs is Tek/Tie2 (Supplementary Fig. 9), which leads us to speculate that these cells represent a rare cell population in tumor-bearing mice known as pro-angiogenic, pro-metastatic Tie2-expressing monocytes [35–41] also found in HCC-bearing liver tissue [42, 43].