Dear Editor,

Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype enriched in cancer stem cells (CSCs), which is characterized by high malignancy and drug resistance. The PI3K/Akt signaling cascade is frequently hyperactivated in cancers. Distinct and non-redundant functions of the three Akt isoforms in tumorigenesis, however, have not been studied extensively. It is noteworthy that despite a few isoform-specific substrates have been identified for Akt1 and Akt2, an Akt3-specific substrate is yet to be discovered. We have previously shown that overexpression of Akt3, but not Akt1 or Akt2, plays an essential role in TNBC growth and therapeutic resistance of breast cancer. However, the role of Akt3 in TNBC CSCs remains unclear.