In this regard, a novel metabolic tumor suppressor, LACTB is shown to reduce mitochondrial phosphatidylserine decarboxylase (PISD) protein abundance and phosphatidylethanolamine (PE)/lysophosphatidylethanolamines (LPE) production, resulting in a mitochondrial state consisted of reduced proliferation, increased epithelial phenotype, and a decrease in mesenchymal and cancer stem cell markers, which associated with tumor regression and inhibition of tumor formation, as demonstrated in in vitro and in vivo breast cancer models in mice and humans. The gene discussed is PISD; the disease is neoplasm.