In conclusion, the single-cell RNA analysis corroborates and extends the immunolabeling data presented above, and establish that Egr2-positive BC cells consist of two major subpopulations: a first one which evolves into SCP and is likely to derive from the NC, and a second one, which gives rise to derivatives with an MC identity and may originate from the mesenchymal precursors of meningeal fibroblasts. Here, EGR2 is linked to breast cancer.