TNFRSF17 and sarcoma: APRIL has a higher affinity for BCMA than BAFF (12), and both of them can activate the downstream signals of BCMA like nuclear factor kappa-B (NF-κB) (13), rat sarcoma/mitogen-activated protein kinase (RAS/MAPK), and phosphoinositide-3-kinase–protein kinase B/Akt (PI3K-PKB/Akt) (14), thus promoting the expression of antiapoptotic proteins (e.g., Mcl-1, BCL-2, BCL-XL) and the activation of specific signaling pathways or factors (e.g., cell adhesion molecules, angiogenesis factors, immunosuppressive molecules) about cells’ proliferation (14).