The article by Michael Zeisberg and Eric G. Neilson discusses the concept of epithelial-mesenchymal transition (EMT) and its various subtypes, emphasizing the importance of context and biomarkers in identifying different types of EMT. They highlight that EMT involves the transformation of epithelial cells into motile mesenchymal cells, which can occur in three distinct contexts: primitive embryonic development, tissue fibrosis, and cancer metastasis. The authors propose that these three types of EMT can be distinguished based on the phenotype of the output cells and the context in which they occur. They also review the biomarkers that can be used to identify EMT, including cell-surface markers, cytoskeletal proteins, extracellular proteins, transcription factors, and microRNAs. The article emphasizes the need for a comprehensive set of criteria to ensure that researchers are studying the same phenomenon across different experimental conditions.The article by Michael Zeisberg and Eric G. Neilson discusses the concept of epithelial-mesenchymal transition (EMT) and its various subtypes, emphasizing the importance of context and biomarkers in identifying different types of EMT. They highlight that EMT involves the transformation of epithelial cells into motile mesenchymal cells, which can occur in three distinct contexts: primitive embryonic development, tissue fibrosis, and cancer metastasis. The authors propose that these three types of EMT can be distinguished based on the phenotype of the output cells and the context in which they occur. They also review the biomarkers that can be used to identify EMT, including cell-surface markers, cytoskeletal proteins, extracellular proteins, transcription factors, and microRNAs. The article emphasizes the need for a comprehensive set of criteria to ensure that researchers are studying the same phenomenon across different experimental conditions.