Using the same iPSC markers, we have also shown the presence of two CSC subpopulations within head and neck metastatic malignant melanoma (HNmMM): an OCT4+/SOX2+/KLF4+/c-MYC+ CSC subpopulation within the TNs, and another in the PTS with NANOG present only in two of the 20 cases studied (44). Here, KLF4 is linked to metastatic melanoma.