On the other hand, several studies demonstrate a cancer promoting effect of complement activation fragments, either through recruitment of immunomodulatory cells like myeloid-derived suppressor cells [25], or by directly interacting with receptors (e.g. C3aR, C5aR) that activate growth signalling pathways like ERK1/2, or EGFR transactivation [26, 27]. This evidence concerns the gene C5AR1 and cancer.