KDR and neoplasm: Tumor-derived exosomes containing proteins, miRNAs, and lncRNAs can directly promote angiogenesis by activating the vascular endothelial (VE) growth factor (VEGF)/VEGF receptor (VEGFR) pathway or indirectly promote angiogenesis by the tissue plasminogen activator (tPA)-dependent pathway, Notch pathway, WNT5A pathway, and Janus kinase (JAK)-STAT pathway, which play important roles in cancer development (Figure 1).32