Among the transcription factors, Oct-4 is highly expressed in bladder cancer [220]; Sox2 is found in breast tumours and activated in breast cancer stem cells [221]; Nanog has been shown to be related to brain and other kinds of cancer stem cells [194]; and KLF4 is required for maintenance of breast cancer stem cells and for cell migration and invasion [222]. Here, KLF4 is linked to breast carcinoma.