HES1 and breast cancer: EZH2 can activate NOTCH signaling in breast cancer38, mutation of NOTCH1 can lead to repression of PTEN through the HES-1 transcription factor in T cells23,43, and NOTCH1/2 translocations and mutations in breast cancer can increase activity or create a truncated form of NOTCH resembling cleaved NOTCH that enters the nucleus to regulate transcription of target genes32,44.