PRODH and breast cancer: To explore the ability of orally administered N-PPG to penetrate the blood–brain barrier in sufficient amounts to induce partial degradation of brain PRODH and potentially activate the UPRmt in mouse brain tissue, we chose treatment doses based on our previous mouse study wherein repeated administration of 50 mg/kg of N-PPG by either oral, intravenous or intraperitoneal routes was not only well tolerated but also able to downregulate PRODH protein levels in both normal host cells (kidney) and in xenografted human breast cancer cells (Scott et al. 2019).