In this seminar, I will describe my lab's recent advances in three areas. First, I will focus on the mechanisms of acquired resistance to an HSP90 inhibitor drug, Ganetespib, in HER2-positive breast cancer. Second, I will describe how p63, an epithelial gatekeeper gene, regulates pregnancy-associated HER2-positive breast cancer via its tumor-initiating cells PIMECs (pregnancy-induced mammary epithelial cells). Finally, I will give an overview of our novel discoveries of how p63 regulates normal ...