KLF4 and skin squamous cell carcinoma: However, it has also been reported that KLF4 may be an oncogene in a few types of cancers, such as breast cancer and skin squamous cell carcinoma [11, 12], suggesting that KLF4, similar to transforming growth factor-β and Notch, may have opposing roles in tumorigenesis and progression in a context-dependent manner [13, 14].