Building on basics

Mixing and matching
(continued)

And new treatments are desperately needed. Conventional chemotherapy works by targeting the DNA of rapidly dividing cells. These drugs can be very effective, but side effects are common and they are less effective in metastatic cancer.

One new class of drugs, cell cycle modulators, has shown promise in targeting cancer cells while leaving their healthy neighbors alone. The drugs interrupt the signals that make cancer cells proliferate, keeping them in a kind of holding pattern.

Cyclin dependent kinase (cdk) inhibitors, one type of cell cycle modulator, contain enzymes that target altered genes and regulate their dysfunction. Another type, antimi- crotubial agents, halt cells at just the moment in mitosis when they are about to split. They do this by preventing the development of microtubials, protein filaments that help cells maintain their shape before nuclear division.

Sending a "stop!" signal to cells on a rampage to grow, grow, grow doesn't just slow them down - it kills them, according to Gumerlock.

"In adults, most cells don't divide rapidly, and cell cycle modulators don't do much to them," Gumerlock explains. "The cells just sort of sit there. But when you give those drugs to cancer cells, the conflicting signals causes them to die."