Fig. 3.

ThPOK-mediated lymphomagenesis requires DN-to-DP developmental transition. (A) Survival plots of ThPOK^const mice crossed to Rag2^+/+, Rag2^−/−, or αβTCR Tg⁺ Rag^−/− backgrounds, as indicated. (B) FACS analysis of γδTCR Tg⁺ (KN6⁺) Rag2^−/− β2m^−/− and γδTCR Tg⁺ (KN6⁺) Rag2^−/− H-2d/d thymocytes in presence or absence of ThPOK^const transgene, showing CD4, CD8, γδTCR, and TCRβ expression. Note that due to RAG deficiency there is no rearrangement of endogenous TCR genes in these mice, so that TCRβ expression is lacking. (C) Survival plots of ThPOK^const mice crossed to KN6⁺ RAG^−/− B2m^−/− (ligand negative) or KN6⁺ RAG^−/− H-2d/d (ligand positive) backgrounds, as indicated. Note that all ThPOK^const KN6⁺ RAG^−/− B2m^−/− mice died by 200 d, and those examined showed clear thymic lymphoma, whereas no mice from other groups showed evidence of lymphoma. (However, a few of these also died, likely from infection.)