Alex L. Kolodkin

Leader in axon guidance. Identified the first members of the semaphorin family, the largest and one of the most widely used classes of axon guidance molecules. Subsequently, pioneered the identification of mechanisms by which semaphorins act to guide axons. Codiscovered the neuropilins, the first semaphorin receptor; showed that certain semaphorins use integrins as receptors; discovered important downstream signaling molecules including MICAL (an enzyme that regulate cellular redox state), protein kinase A, MAP kinase; demonstrated that while most semaphorins act as repellents, some act as attractants. His work also revealed the numerous biological processes that semaphorins participate in, from the fruit fly central and peripheral nervous systems to the mammalian retina, from axon pathway choice to synapse formation and pruning of exuberant axons.