PROM1 and neoplasm: The former have been conceived as simply represented by endothelial cells associated with Nestin+ and CD133+ stem cells, which condition angiogenesis and tumor growth [6], or as more complicated structures including, beside tumor stem cells, endothelial cells, astrocytes, fibroblasts, macrophages, pericytes, non-stem tumor cells, and microglia [3] (Figure 1).