Researchers at the University of Illinois Chicago have identified a molecular switch that helps determine whether cancer cells remain soft and difficult to destroy or become stiff enough for the immune system to attack.

The study, led by researchers in the College of Medicine and published in the journal Developmental Cell, sheds new light on how the physical properties of cancer cells influence metastasis—the spread of cancer—and points to a promising new therapeutic target.

“The physics of cancer are very counterintuitive. The outer shell of a tumor is very rigid: Even patients can feel the hardness of a growing tumor lump,” said Ekrem Emrah Er, assistant professor of physiology and biophysics and senior author of the study. “But the individual cells inside the tumor are very soft and flexible and gooey, which allows them to kind of leak out. Then they disseminate and metastasize to different organs.”