A new study suggests that CD133, a glycoprotein, has a negative effect on the growth of synovial sarcoma cells:
http://www.ncbi.nlm.nih.gov/pubmed/22571340
According to a previous study, this CD133 is considered a biomarker of cancer stem cells:
http://www.ncbi.nlm.nih.gov/pubmed/19752721
In neuroblastoma, CD133 expression was associated with chemoresistance:
http://www.ncbi.nlm.nih.gov/pubmed/22394107
More information about CD133: