This anti-tumor effect was hypothesized to be the result of a specific immune response as it was not observed in immunodeficient mice (T-cell deficient, nude mice), was tumor-type specific (growth of a second graft of a different cell line was not affected by irradiation of the first graft), and synergized with administration of the FMS-like tyrosine kinase 3 (Flt-3) ligand. This evidence concerns the gene FLT3 and neoplasm.