Epithelial-to-mesenchymal transition (EMT) is a fundamental process that is widely employed during development, including during gastrulation, neural crest migration, and cortical development. EMT is also important in wound healing and pathological conditions such as cancer metastasis and organ fibrosis. Lavin et al. (e00183-21) provide a comprehensive study investigating the kinetics and potential function of many basic helix-loop-helix (bHLH) transcription factors during EMT in mammary epithelial cells. They show that Mnt is induced during EMT and is essential for the process. Mnt promotes EMT by recruiting histone deacetylase 1 and repressing target genes underlying epithelial identity via epigenetic mechanisms.