ANGPT2 and neoplasm: However, Tie2-expressing monocytes (TEMs), a subpopulation of circulating, tumor-infiltrating myeloid cells with a highly proangiogenic phenotype, have been found in both humans and mice.12 Angiopoietin 2 (Ang-2), a Tie2 ligand, is overexpressed by ECs in tumors, further augmenting the ability of TEMs to stimulate angiogenesis through upregulation of proangiogenic enzymes, such as thymidine phosphorylase and cathepsin B.13, 14