C3AR1 and osteosarcoma: Figure 4B listed the top 30 mRNAs according to degrees, which were considered as hub mRNAs. Univariate cox regression analysis showed that 32 stromal and immune mRNAs had significant correlations to prognosis of osteosarcoma (Figure 4C). After integration of hub mRNAs and prognosis-related mRNAs, we obtained 12 hub and prognosis-related mRNAs (C1QA, C1QB, ITGAM, C1QC, LY86, C3AR1, CD163, CD14, FCGR2A, TREM2, SIGLEC1, and VSIG4) for osteosarcoma (Figure 4D), which could play key roles in osteosarcoma progression.