NOTCH regulates T-LiC activity in vivo. (A) Design of the experiments. (B,C) Analysis of human CD45⁺ cell engraftment in the IBM of mice transplanted 3 months before with M18, M22 (B), and M30 (C) T-ALL cultured during 30 days in contact with MS5-GFP, MS5-DL1 in presence (+GSI: 1 or 4 weeks), or in absence (−GSI/DMSO: 1 or 4 weeks) of GSI. Each mouse received all the cells obtained from one culture well directly into one femur. At the time of death, IBM was analyzed separately from the rest of the BM. (D) Phenotype of human CD45⁺ cells engrafting different mouse hematopoietic organs after transplantation of MS5-DL1/cocultured M18 (left panels) and M30 (right panels) T-ALL leukemic cells. SPL indicates spleen. (E) γ-TCR gene rearrangement of M30 T-ALL at diagnosis and after coculture with MS5-GFP (GFP) or MS5-DL1 (DL1) cells. Results obtained with human cells recovered from the SPL of mice transplanted with cells cocultured with MS5-DL1 (Mice/DL1) or MS5-GFP (Mice/GFP) are also shown. Controls are as in Figure 1.