The surgically resected tumor specimens were immediately implanted subcutaneously into NOD/SCID/IL2Rγ null (NSG) mice as passage 1 (P1) generation PDXs; tumors from established P1 PDXs were then transplanted to other NSG mice as passage 2 (P2) generation PDXs and so on (Figure 1). The gene discussed is IL2RG; the disease is neoplasm.