Cantharidin is a toxic compound, isolated from the Spanish fly or blistering beetle (Lytta (Cantharis) vesicatoria) and other insects. It is a potent and specific inhibitor of protein phosphatases 1 (PP1) and 2A (PP2A). Cantharidin is a medication used to remove warts and a viral skin infection called molluscum contagiosum. It is made from the secretions that come from the green blister beetle in combination with salicylic acid. It works by creating a blister just below the wart, which pushes the wart up and away from the underlying tissue, cutting of the blood supply to the wart. As the blister and the wart dry out, they both slough off, leaving fresh, unmarred skin behind. It is also used as an experimental anti-tumor agent. Several studies also show potential novel applications of cantharidin in acquired perforating dermatosis, acute herpes zoster, and leishmaniasis. In 1962, cantharidin lost Food and Drug Administration (FDA) approval owing to the failure of its manufacturers to submit data attesting to cantharidin's efficacy. However, in 1999, the FDA included cantharidin on its “Bulk Substances List” of drugs which although not available as commercial products, were approved for compounding on a customized basis for individual patients.