The second wave of downregulation included the Wnt-responsive transcription factor Hnf1 (Tcf1), with a well characterised role in T cell development and T-ALL [34, 35], and Smad7, also involved in T-ALL [36], whereas the third wave contained genes that have been less extensively studied in thymocytes. This evidence concerns the gene SMAD7 and acute lymphoblastic leukemia.