HES1 and acute lymphoblastic leukemia: We next examined the mRNA expression of critical downstream genes of Notch signaling, which are involved in T-ALL cells including Hes1 [19], Pten [22,23], p53 [24], and c-Myc [25,26], and apoptosis-related genes Bcl2, BAX [27], and caspase 3 [28].