View larger image | Recent work suggests primary cilia can sense mechanical forces, such as the flow of urine in the kidneys (shown) or blood in the heart. Those mechanical forces are translated into chemical signals, allowing cilia to communicate with their cells. In a healthy kidney cell, the resulting signal tells the cell not to divide. In people with polycystic kidney disease, though, this message doesn’t get through, leading to improper cell growth. Research now shows that a variety of cilia defects — in signal receptors on the cilium membrane, in molecules responsible for transport within the cilium and in a protein complex called the BBSome, for example — can lead to diseases. Credit: Nicolle Rager Fuller