RAG2 and neoplasm: To determine whether the observed reduction in tumor size and growth observed in mice injected with 4T1-PIP cells is mediated by immune cells, 4T1-PIP and 4T1-EV cells were injected orthotopically into the 4th mammary fat pad of the Rag2/common gamma chain deficient (Rag2−/−γc−/−), a mouse line which lack NK, T and B cells.