To test whether the T-ALL-like disease seen in the IgHμ-TLX1TgPrkdcScid/Scid mice resembled human T-ALL at a molecular level, we assessed the expression of several genes which had previously been shown to be associated with the progression of human T-ALL such as NOTCH1, PTEN and BCL11B[5], [13], [29], [30] in ten tumors isolated from IgHμ-TLX1TgPrkdcScid/Scid and PrkdcScid/Scid mice. This evidence concerns the gene NOTCH1 and acute lymphoblastic leukemia.