CITED2 (CBP/p300–interacting trans-activator with Glu/Asp–rich carboxy-terminal domain-2) is a non-DNA binding transcriptional co-regulator that modulates the activity of multiple transcription factors including p300/CBP, Smad2/3 and estrogen receptor [32,33,34] CITED2 is overexpressed in breast cancer compared to normal mammary tissue and CITED2 was significantly associated with increased incidence of recurrence and breast cancer-specific death of the breast cancer patients [23]. This evidence concerns the gene ESR1 and breast carcinoma.