C3 and neoplasm: The results showed that there was much more TNF-α protein accumulation in both primary and subcutaneous MB tissues compared with the WT normal cerebellum (Fig. 6b) and that when the subcutaneous MB-bearing mice were treated with the C3aR antagonist SB290157, the TNF-α protein level in tumor tissue was reduced significantly compared with the MCT-treated group (Fig. 6b), suggesting that TNF-α might be involved in C3a’s regulation of MB development in vivo.