β-Catenin lymphomas are malignant as well as oligoclonal. (A) Genomic DNA was prepared from LckCre thymocytes (lane 1), LckCre-Ctnnb^Δex3 lymphomas (lanes 2-4), and CD4Cre-Ctnnb^Δex3 lymphomas (lanes 5-8) and digested with EcoRI. Digested DNAs were electrophoresed through agarose gels and blotted onto nitrocellulose. Southern blots were probed with a P³²-labeled 1.2-kb EcoRI-ClaI genomic fragment recognizing the Jβ2 region of the TCRβ gene locus (“Materials and methods”). g.l. indicates the fragment expected for the germ-line TCRβ gene configuration. (B) CD4Cre-Ctnnb^Δex3 thymocytes or CD4Cre-Ctnnb^Δex3– and LckCre-Ctnnb^Δex3–derived lymphomas (2 × 10⁵ cells) were injected into sublethally irradiated Rag2^−/−γc^−/− double knock-out mice by tail vein injection. Injected mice were bled on the day of the injection and then weekly starting at 2 weeks after injection. CD4/CD8 profiles of white blood cells from injected Rag2^−/−γc^−/− mice. Profiles are representative of 2 independent transfer experiments involving 9 recipients and 3 independent tumors (2 CD4Cre-Ctnnb^Δex3 and 1 LckCre-Ctnnb^Δex3). (C) Expression of TCRβ (black) compared to isotype control (gray) or β-catenin (black) compared to isotype control (gray) in DP splenocytes at 5 weeks after adoptive transfer.