Microtubules are essential components for the assumption and maintenance of cell shape, motility, and cell division. Processes that affect microtubule formation can result in genome instability, which can eventually lead to cancer and birth defects in higher eukaryotes. Proper microtubule formation requires regulation of microtubule assembly via functional interactions with several tubulin-binding proteins. Particularly important are the genes regulating early steps in microtubule morphogenesis because it has been shown in the yeast S. cerevisiae that overexpression of beta tubulin monomers leads to toxicity and ultimately lethality. We are using beta tubulin associated lethality to probe for genes that control early steps in microtubule morphogenesis. This research will ultimately lead to a better understanding of microtubules' role in proper cell function.