PROM1 and central nervous system cancer: By contrast, subsequent studies have shown that the CD133-population also have brain tumour initiating properties, suggestive of potential non-hierarchical phenotypic alterations (29–32). Although the field recognises the challenge of identifying a single specific glioma stem marker (originally thought to be CD133) or combination of markers to define a specific developmental duration, it’s possible that stochastic marker expression such as CD133, CD15 and CD44 could confer a survival advantage (33, 34).