The invention generally relates to compounds represented by Structural Formula I: or a pharmaceutically acceptable salt thereof, wherein the variables are as defined and described herein. The invention also includes the synthesis and use of a compound of structural formula I, or a pharmaceutically acceptable salt or composition thereof, e.g., in treatment of cancer (e.g., mantle cell lymphoma), and other diseases and disorders (e.g., PAK-mediated, for example, PAK4-mediated, diseases and disorders).