NPM1 and breast cancer: AP-2γ interacts with nucleophosmin 1 to act as a transcriptional repressor of ERα in endometrial cancer cells.[51] The same mechanism has not been confirmed in breast cancer cells, considering the existence of an association between endometrial and breast cancer.[52] These findings also suggest that the nucleophosmin 1 and AP-2γ complex may function similarly in breast cancer.