Two biophysicists have used supercomputers to show how cell membranes control the shape, and consequently the function, of a major cancer-causing protein. The protein, a small enzyme called K-Ras, is attached to cell membranes where it senses signals that originate outside the cell. During cancer, dysfunctional K-Ras then activates proteins inside the cell that can cause tumor growth and metastasis. K-Ras functions as a troublesome molecular switch, which is perpetually "on" in many cancers, particularly pancreatic cancer. The study not only offers a novel method to study K-Ras, which is only 1/100,000th of an inch across, but also shows how the protein's geometry could explain its role in cancer progression. flower girl outfits of tulle