The myriad classifications for human cells, all running on the same basic biochemical and genetic toolkit, are really an indication of our ignorance of the details of that toolkit and it's complexities. As our knowledge grows, we start to see fascinating experiments like this one, detailed at Medical News Today: "the microenvironments of two human embryonic stem cell (hESC) lines (federally approved) induced metastatic melanoma cells to revert to a normal, skin cell-like type with the ability to form colonies similar to hESCs. The researchers also showed that these melanoma cells were less invasive following culture on the microenvironments of hESCs." Cellular machinery responds to triggers, and we know all too few of them. Exploration of this sort helps move us towards a world in which cancer can simply and easily be turned off.