PTCRA and acute lymphoblastic leukemia: The cluster I genes, which were up-regulated by ICN1 and reverted in the mir-181ab1 null T-ALL DP cells, include numerous genes that are known to be critical for NOTCH (e.g., Dtx1, Notch1, Hes1, Hey1 and Nrarp), pre-TCR (e.g., Ptcra), cytokine and apoptosis pathways (Figure 6C, Table S3).