As shown in Fig. 2f, in order to simulate the concentration gradient of chemokines, agarose gel containing GL261 cancer cell lysate was added to the Y-channel chamber (III) to continuously generate the concentration gradient of chemokines ROS/iNOS, while agarose gel containing bEnd.3 cells lysate was added to the chamber (II), which was used as control34. The gene discussed is NOS2; the disease is cancer.