HES1 and acute lymphoblastic leukemia: Not surprisingly, given the high frequency of Notch activating mutations [3, 26] and the role of IL-7 in T-ALL, this profile was associated with increased Notch activation and increased availability to respond to IL-7, as indicated by higher average expression of Notch1 and its targets Hes1 and IL-7r, respectively (Fig. 5a, left, right, and far right panels).