It promotes tumor growth in a variety of cancers.[56] PTBP1 is highly expressed in breast cancer and its expression is associated with a poor prognosis in patients.[57, 58] A recent study has shown that PTBP1 can bind to FOXO1 mRNA[43] and XPO1 can bind to PTBP1.[42] Our recent study revealed that FOXO1 is highly expressed in BLBC and promotes tumor growth by increasing KLF5 transcription.[40] This study revealed that XPO1 can synergistically promote the nuclear export of FOXO1 mRNA by interacting with PTBP1, ultimately leading to increased transcription of KLF5 (Figure 5). Here, FOXO1 is linked to breast cancer.