Indeed, transcriptome analysis of the breast CTC clusters shows the enrichment of TGF‐β and EMT signatures, suggesting that CTC clusters, which are oligoclonal and held together through cell–cell interactions, most likely arise through collective migration of tumor cells, a process dependent on partial EMT (Aceto et al., 2014; Friedl and Gilmour, 2009; Yu et al., 2013). The gene discussed is TGFB1; the disease is neoplasm.