After the modified T cells are infused into the patient, they home into the bone marrow (this tracking is monitored by special radiological techniques) where the new protein receptor on the T cell surface can recognize and bind to the cancer cells (which express Lewis Y). Once bound onto the cancer cells, the T cells get activated and subsequently replicate and kill the cancer cells. The novelty of this approach is that the T-cells will only kill cells that have the Lewis Y on their surface - the cancer cells. Moreover, because there are few normal cells in a person's body that carry Lewis Y, this treatment is likely to only have minor side effects.