These include reconstituting immunodeficient mice with mature immune cells (i.e., PBMCs or tumor-infiltrating lymphocytes) prior to transplanting patient tumor tissue containing human stromal cells along with any tumor-infiltrating human immune cells, while other groups have begun developing “humanized mice” reconstituted with human CD34+ hematopoietic stems cells (HSCs) following sub-lethal irradiation in immunodeficient mice, thereby repopulating them with a largely human immune system that includes B and T lymphocytes as well as myeloid cells [55, 149, 150, 155–159]. This evidence concerns the gene CD34 and neoplasm.