Freshly resected primary and metastatic colorectal cancers (CRC) [1], [2], like many other types of human hematologic and solid tumors, can be established as xenografts in immune-deficient mice such as the NOD/scid/IL2Rγ−/− (NSG) strain and propagated long-term via serial transplantation. This evidence concerns the gene IL2RG and colorectal carcinoma.