After a S.H.I.E.L.D. team led by Agent Jesse Drew was attacked by venomous alien spider parasites on the Moon, only Jesse managed to escape back to Earth. The infection turned his blood into black ooze and threatened to kill him, but his life was saved by Cindy Moon, who developed Radioactive Spider Isotopes that stabilized Jesse's condition and granted him spider-like powers; however, Cindy lied to Jesse and convinced him that he required regular injections of her isotopes in order to survive. Both of them splintered off from S.H.I.E.L.D. and formed S.I.L.K., an international crime organization. While Jesse only retained for powers for a few hours after the isotopes injection, S.I.L.K. eventually developed and released into the wild a Radioactive Spider, based on the isotopes, which bit Gwen Stacy and granted her permanent powers, leading to Gwen taking on the mantle of Spider-Woman all while Cindy Moon continued to observe her.
When Gwen confronted Cindy face-to-face, she was prepared and took Gwen's powers away from her with her Power Glove. Eventually Gwen learned and revealed to Jesse that Cindy lied to him about needing the isotopes to survive. Jesse decided to abandon S.I.L.K. and went on the run, but left his remaining isotopes to Gwen so that she could continue to act as Spider-Woman until the supply ran out. Elsa Brock, seeking a way to neutralize the Lizard Serum - itself derived from Cindy's research into the alien spider venom's mutagenic properties - discovered that exposing it to the Radioactive Spider Isotopes caused it to mutate into an amorphous symbiotic entity closely resembling the alien spider parasites' venom.
- 11 appearance(s) of Radioactive Spider Isotopes
- 9 minor appearance(s) of Radioactive Spider Isotopes
- 3 mention(s) of Radioactive Spider Isotopes
- 1 mention(s) in handbook(s) of Radioactive Spider Isotopes
- 1 image(s) of Radioactive Spider Isotopes