Recent genetic evidence suggests that tyrosine kinases and tyrosine phosphatases can control the guidance of specific growth cones. Within a family of related phosphatases or kinases, individual members can have partially redundant functions. Receptor phosphatases can work together at one guidance choice point, but in opposition at another. The specific combination of kinases and phosphatases active in a growth cone may be an important determinant of pathway choice. One mechanism by which these proteins could control guidance decisions is through regulation of adhesion between growth cones and axons.