(A) Scatter plot showing the correlation of the mean EMP signature gene expression of the primary tumor and metastatic cells colored by tumor. Linear regression with 95% CIs and Pearson’s correlation coefficient are shown. (B) Violin plot showing the EMP signature per tumor ordered by metastatic potential using the Smart-Seq2 data set. (C) Bubble plot showing the correlation of the EMP signature with PCs 1–5 using the Smart-Seq2 data set. (D) UMAP projections of single-cell transcriptomes for individual tumors are color coded by the magnitude of EMP signature gene expression. (E) Cells in the Smart-Seq2 data set ranked by the EMP signature exhibited 3 cell states: epithelial-like (blue), intermediate EMP (purple), and mesenchymal-like cells (red). (F) Bar chart showing the proportion of EMP cell states in each tumor ranked by the increasing proportion of mesenchymal-like cells. Grayscale boxes indicate the metastatic potential. Other annotations indicate ER status and BC subtype. The Smart-Seq2 data set is shown. (G) Violin plots show the expression of EMT-associated TFs in cells expressing these TFs, grouped by EMP cell state (Epi, epithelial-like; Inter, intermediate EMP, Mes, mesenchymal-like cells). Bar charts show the fraction of TF-expressing cells colored in gray. The Smart-Seq2 data set is shown.