Abstract: Cells must complete intricate mechanical tasks during a wide variety of biological processes ranging from the segregation of chromosomes during mitosis to forming and maintaining the axon and dendrites in neurons. To accomplish these diverse tasks, cells have evolved complex networks of force-generating and load-bearing elements in the form of the dynamic cytoskeleton. Consisting of elements such as microtubules, actin filaments, and a host of motor and non-motor proteins, these networks can perform mechanical work and transmit forces that push and pull cellular components. These networks span micron-scale distances, yet are built from nanometer-sized proteins that are 1000s of times smaller than the network itself. How these individual "building blocks" work collectively as ensembles to perform distinct mechanical tasks and allow the cell to maintain its structural integrity under load is unclear, as directly characterizing forces in this context has proved challenging. The Forth lab aims to bridge this critical knowledge gap by building these networks out of purified components and directly measuring their response to applied forces using biophysical tools such as optical tweezers and single molecule fluorescence microscopy. In this talk, I will describe how our lab at RPI has worked to understand the mechanical functions of essential microtubule crosslinking proteins across a range of biological processes.