KLF4 and melanoma: Melanoma cells cultured long-term in an acidic environment also demonstrated the induction of self-renewal and pluripotency markers (e.g., Nanog, KLF4 (Krüppel-like factor 4), OCT4 (octamer-binding transcription factor 4), and SOX2) as well as the overexpression of the cancer stem cells markers (e.g., CD133, CD243, and ALDH1A1) (Figure 2).