The mechanism of the selective antivascular effect of ASA404 in the tumor vasculature is not well understood but it has been proposed that these effects are mediated by intratumoral induction of several cytokines including tumor necrosis factor-α (TNF-α), granulocyte-colony-stimulating factor (G-CSF), interleukin 6 (IL-6), macrophage inflammatory protein 1α (MIP-1α) [7,8], increased plasma serotonin concentration [9] and induction of intratumoral nitric oxide synthase [10]. The gene discussed is IL6; the disease is neoplasm.