HES1 and breast cancer: Upon Notch signaling activation, the intracellular domain of the Notch protein (NICD) translocates into the nucleus and binds to its transcriptional effector, recombination signal-binding immunoglobulin kappa J region (RBPJ), resulting in the transcription of Notch target genes, such as the proto-oncogene c-Myc and hairy enhancer of split 1 (HES1), which are associated with the differentiation of hematopoietic cells and CML-BC transformation [8, 10, 11].