C5 and neoplasm: However, recent studies have demonstrated the expression of complement components C3 and C5 and the anaphylatoxins C3a and C5a in several types of tumors (12, 14, 46) and their role in promoting tumor growth (46, 47), angiogenesis, metastasis (48, 49), immunosuppression, inhibition of T-cell responses (14, 50), and regulatory cell recruitment [myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs)] (51, 52).