(142) found that after the addition of normal human serum, human bone osteosarcoma epithelial cells (U2-OS) activated the alternative pathway of the complement system, resulting in the generation of more vascular endothelial growth factor-A and fibroblast growth factor 1 and promotion of angiogenesis in models in vitro, regulated by the phospho-ERK signaling pathway. Here, VEGFA is linked to osteosarcoma.