Ingenol mebutate is a diterpene ester derived from the plant Euphorbia peplus and is FDA approved for the topical treatment of actinic keratoses (AK). Shown to be efficacious with as little as a 3-day trial, this compound is being further tested for the topical treatment of other nonmelanoma skin cancers with promising preclinical data. In an effort to elucidate the molecular mechanism of this novel drug, Stahlhut et al. (2012) suggest a role for calcium and apoptosis. Further studies are needed to evaluate the intracellular mechanisms of ingenol mebutate-mediated cytotoxicity. Additionally, studies such as this not only shed light on the mechanism of ingenol mebutate and its derivatives, but also pave the way for evaluating the involvement of the immune system in eliminating drug-treated cells and tissues. This has important implications for the development of novel topical immune modulatory products and the field of topical immunotherapy.