Like bustling cities, plant and animal cells depend upon differentvehicles to deliver cargo to the right place at the right times. These intracellular vehicles are motor proteins, believed to transport working components along tracks known as microtubules. A new motor protein has been purified from its natural host cell in its active state, according to a recent report in the journal Nature by a UC Davis research group that included two undergraduates. Previously, certain motor proteins had been isolated genetically, and expressed and studied outside of their native environments, akin to studying a butterfly on a pin or a bird in a cage. These findings verify a new method for detecting members of a large family of motor proteins known as kinesins. Research in this fast-moving field eventually is expected to yield insights into certain disease states, such as cancer and birth defects, caused by malfunctions in the intracellular transport system. "Things don't just float around in a cell," says Jonathan Scholey, a professor of molecular and cellular biology at UC Davis, "they're put into position by motor proteins, which are fundamental to the structure and function of a cell."