CCND1 and breast cancer: The KLF5 transcription factor is highly expressed in BLBC.[10] Our previous studies showed that KLF5 promotes breast cancer cell cycle progression and tumor growth through upregulating the transcription of Cyclin D1, FGF‐BP1, mPGES1, and TNFAIP2[11, 12, 13] and downregulating the transcription of cell cycle inhibitors, including p21 and p27.