We noted that BMAL1 and CLOCK protein levels varied among T-ALL cell lines and that levels of both transcription factors were higher in SUP-T1, JURKAT, MOLT4, DND41, KOPTK1 and CUTLL1 cell lines and lower in RPMI-8402, PF382 and HPBALL cells. This evidence concerns the gene CLOCK and acute lymphoblastic leukemia.