T-ALLs from TAL1xLMO1xp16INK4A mice express clonal TCRβ rearrangements and p16INK4A transgene chromosomal deletion. (A,B) TCRβ rearrangements in tumor DNA from our different models are detected by Southern blot after SstI digestion (1 experiment). Germ line bands are indicated with arrows, and tumor samples are identified using unique sample numbers. The numbers 67, 75, and 55 are p16TLM leukemias; 213, 16, 155, 36, 177, and 22 are TLMpTαko leukemias; and 14, 15, and 21 LMO1 are pTαko leukemias. T indicates tail; L, liver (germ line control); and M, size marker. (C,D) Southern-blot analysis of p16 locus configuration using p16 probe and SstI (C) or EcoRI (D) digests of DNA. (Cross hybridization occurs between human and mouse.) Tumor samples are identified as in panels A and B. DNA from WT, p16 transgenic mice are used as controls. Bands corresponding to the human transgene and to the endogenous locus are shown (1 experiment).