CFP and neoplasm: We found that while both YFP positive (CSC derived) and CFP positive (non-stem derived) were detectable, the overwhelming majority of tumor cells were derived from CSCs; 94.5 percent of Tra-1-85 positive cells within the tumor were YFP positive (CSC derived) versus 0.2 percent which were CFP positive (non-stem derived, Fig. 3A, B).