472 Do we hit the target? Phospho-reactome measurements determine efficacy of targeted therapies

negative regulator of CD133. In addition, p53 directly binds on the CD133 promoter and suppresses its promoter activity, showing that CD133 could be a novel target gene of p53. Furthermore, CD133 is necessary for tumor formation and growth of cancer cells, and these functions of CD133 are obstructed by overexpression of p53. Conclusions: These results suggest that p53 is a key modulator for CD133 expression in CSC, and provide novel perspective on targeting CSCs for the cancer therapy.