Metastasis accounts for over 90% of breast cancer-associated mortality. Elucidating the pro-metastatic changes that occur within breast tumor cells and the surrounding tumor microenvironment (TME) is imperative for the development of antimetastatic therapies. This dissertation characterizes the effects of elevated H2O2 in the breast TME and cell-intrinsic alterations in the microtubule cytoskeleton for their impact on metastatic potential. H2O2 exposure induces -tubulin detyrosination and acetylation, two markers of poor patient prognosis, via a conserved Ca2+-dependent mechanotransduction pathway. H2O2 induces the formation of microtubule-based microtentacles (McTNs) which are enriched in detyrosinated-tubulin and acetylated-tubulin, but inhibits McTN-mediated functions of cell clustering and reattachment. This dissertation also elucidates the function of specific subsets of microtubules that have been post-translationally detyrosinated in breast cancer. Detyrosinated microtubules may provide an improved therapeutic target compared to current microtubule-stabilizing agents, which indiscriminately target all microtubules and are associated with broad side effects and inadvertently increase metastasis. Leveraging the recent discovery of the tubulin carboxypeptidase (TCP) enzyme, this study demonstrates the feasibility and functionality of lentiviral-based, constitutive TCP overexpression in mammary epithelial cells. TCP overexpression increases detyrosinated-tubulin, which is accompanied by morphological changes and enhanced cellular reattachment and migration. Collectively, this dissertation establishes that H2O2 signals in the TME induce microtubule stabilization and affect metastatic phenotypes, and provides the tools and preliminary data to continue investigating the therapeutic potential of targeting -tubulin detyrosination to reduce breast cancer metastasis.