This hypothesis was later applied to a cancer cell setting as demonstrated by several studies, e.g., in epithelial CSCs and neuroblastoma [191,192], although others have shown that, for instance, SOX-2 is not crucial for the reprogramming of primary mouse melanocytes and melanoma cells into induced pluripotent stem cells [193], neither for primary tumor formation nor metastatic spreading [194]. This evidence concerns the gene SOX2 and melanoma.