Cancer cells are equipped with a kind of suicide pill: a protein on their surfaces that gives them the ability to send an eats me signal to immune cells. To figure out how to coax cancer cells into emitting the signal rather than a dangerous “don’t eat me” signal.

Science Translational Medicine reports that the cells send out the enticing “eat me” signal by displaying the protein calreticulin. But another molecule, called CD47, allows most cancer cells to avoid destruction by sending the opposite signal: “Don’t eat me.” An antibody blocks CD47 turning off the signal could help fight cancer, but mysteries remained.

Many normal cells in the body have CD47, and yet those cells are not affected by the anti-CD47 antibody, the anti-CD47 antibody treatment selectively killed only cancer cells without being toxic to most normal cells.

Now, they shown that calreticulin exists in a variety of cancers, including some types of leukemia, non-Hodgkin’s lymphoma and bladder, brain and ovarian cancers. “This research demonstrates that the reason that blocking the CD47 ‘don’t eat me’ signal works to kill cancer is that leukemias, lymphomas and many solid tumors also display a calreticulin ‘eat me’ signal,” They also shows that most normal cell populations don’t display calreticulin and are, therefore, not depleted when we expose them to a blocking anti-CD47 antibody.”

The next step is to understand how calreticulin works. “We want to know how it contributes to the disease process and what is happening in the cell that causes the protein to move to the cell surface,” Any of these mechanisms offer potential new ways to treat the disease by interfering with those processes.