TAL1 and acute lymphoblastic leukemia: In the set of 13 initial disease/relapse pairs TAL1-driven T-ALLs were exclusively identified in those patients developing type-2 relapses (4/8 type-2 vs. 0/5 type-1; p = 0.1; Fisher's exact test, two-tailed) suggesting that TAL1 may play a specific role in type-2 T-ALL relapses (Fig. 3, Fig. 5), although clearly this trend will have to be validated in a larger number of samples.