'Our premise is that mechanics play a role in almost all biological processes, and with these DNA-based tension probes we're going to uncover, measure and map those forces,' says biomolecular... Adherent cells, the kind that form the architecture of all multi-cellular organisms, are mechanically engineered with precise forces that allow them to move around and stick to things. Proteins called integrin receptors act like little hands and feet to pull these cells across a surface or to anchor them in place. When groups of these cells are put into a petri dish with a variety of substrates they can sense the differences in the surfaces and they will "crawl" toward the stiffest one they can find.

Encapsulated toxin-producing stem cells (in blue) help kill brain tumor cells in the tumor resection cavity (in green). Harvard Stem Cell Institute scientists at Massachusetts General Hospital have devised a new way to use stem cells in the fight against brain cancer. A team led by neuroscientist Khalid Shah, MS, PhD, who recently demonstrated the value of stem cells loaded with cancer-killing herpes viruses, now has a way to genetically engineer stem cells so that they can produce and secrete tumor-killing toxins.

This image shows, from the left: Katherine Jones, Salk professor, and first authors Yupeng Chen and Lirong Zhang. Like a slumbering dragon, HIV can lay dormant in a person's cells for years, evading medical treatments only to wake up and strike at a later time, quickly replicating itself and destroying the immune system.