KLF4 and colonic neoplasm: Tumor spheroid models derived from sporadic colon cancer cell lines have been utilized to identify stem cell specific molecular markers including octamer binding transcription factor-4 (Oct-4), Kruppel-like factor-4 (Klf-4), sex determining region Y-box-2 (SOX-2) and cellular Myc (c-Myc) [44,45].