Although IL-12 is regarded as one of the most powerful immunostimulatory cytokines, IL-12 gene therapy could still be improved by combination with some other immunotherapeutic modalities employing cytokines, for example, with IL-2 [108] and lymphotactin [112] released by tumor cells following the intratumoral injection of adenoviral vectors and with tumor vaccine expressing IL-18 [109]. The gene discussed is XCL1; the disease is neoplasm.