Provided herein are methods and assays relating to the diagnosis and treatment of a taxane-resistant cancer. Such methods and assays comprise determining the level of expression of miR-135a in a biological sample from a subject having or suspected of having a taxane-resistant cancer or from a subject that was or is being treated with a taxane anti-cancer agent. Also provided herein are methods for treating such cancers by administering an inhibitor of the miR-135a pathway and a taxane to a subject in need thereof.
