Here we found that BDNF promoted the secretion of PTX3 from gastric cancer cells in humans (Figure 3) and, in turn, PTX3 induced RANKL secretion from OBs to further amplify OC formation in a co-culture system (Figure 4), thereby mimicking the BM environment [47] and reinforcing the idea that BDNF and PTX3 likely contribute to the bone-destructive process and disease progression in gastric cancer. The gene discussed is TNFSF11; the disease is gastric cancer.