Protein keeps cancer idling, not hitting gas.

• Position: Cancer Supression - Brief article

A protein which intimately is involved in cancer-promoting cell signaling also keeps a key component of the signaling pathway tied down and inactive, reports Nature Structural Molecular Biology. She, pronounced "schick," plays a key role in activating signals that lead to cell proliferation (and cancer) when cells are stimulated. However, it unexpectedly turns out to be a tumor-suppressor as well, keeping Erk (extracellular-signal-regulated kinase) under wraps when a cell is less active, says biochemist John Ladbury, senior author of the research.

"She is a checkpoint to prevent out of control cell growth, binding to Erk when a cell is not being stimulated by growth factors. Otherwise, the lower-level background signaling that's always present in a cell would be uncontrolled."

Overexpression of Erk occurs in many types of cancer, including ovarian, prostate, and Hodgkin lymphoma, so cellular control of its activity is important.

In the absence of external stimulation by growth factors, cells remain active but lower levels of cell signaling...