Researchers say they have eliminated leukemia cells in mice by shutting off a molecule necessary for the cancer cells’ survival. Reporting in the Sept. 21 issue of the journal Cancer Cell, scientists said the experiment confirms that cancer calls cannot remain malignant in the absence of the molecule, known as BCL-2, which fights cell death. When it is shut off, the cancer cells self-destruct. “Turning off BCL-2 is an effective thing to do if you want to kill cancer cells,” said Dr. Anthony Letai, an instructor in medicine at Dana-Farber Cancer Institute in Boston and the study’s lead author.