Which of these is a possible risk associated with stem cell therapy?

Is what I found ...

As with any treatment, there are certain risks to stem cell therapy, including immune rejection of the cells used in treatment. Stem cells have the potential to divide many times and differentiate into many cell types, which is their great promise. Paradoxically, because of these abilities, stem cells also have the potential to form tumors. These potential risks dictate that both doctors and patients proceed with caution, and thus it is critically important that further research is conducted.