C3 and osteosarcoma: When ‘Degree ≥ 4’ was set as the cut‐off criterion, eight genes in the PPI network were selected as hub genes: IL8, CXCL2, PTGS2, FOS, CXCL1, C3, EHMT2 and PGF. These hub genes might play crucial roles in the mechanism of sorafenib inhibition of osteosarcoma.