In particular, urokinase plasminogen activator (uPA) and urokinase plasminogen activator receptor (uPAR) are shown to be involved in the migration of NSCs to malignant tumors, as well as various cytokines including interleukin-6 (IL-6), interleukin-8 (IL-8), and monocyte chemoattractant protein-1 [12–14]. Here, IL6 is linked to cancer.