RAG2 and sarcoma: The importance of innate immunity in driving cancer immunoediting, even without adaptive immunity, was established in a study more than ten years ago by comparing spontaneously arising sarcomas induced by methylcholanthrene in wild-type mice, adaptive immune-deficient Rag2−/− mice and Rag2−/−γc−/− mice, which lack all lymphocytes (O’Sullivan et al, 2012).