After losing his mother to cancer, Modeyso developer Dr. Joshua Allen became fascinated by cancer defenses that already exist in the human body. “Evolution has been working on the cancer problem for a long time, a lot longer than humans,” Allen tells Popular Science. Evolution has given the human immune system ways to recognize and get rid of tumor cells. TRAIL genes are naturally produced by our bodies, and selectively trigger cell death in cancer cells. The fusion of TRAIL and luciferase became a biological flashlight, making cancer cells glow.