Importantly, RFP/CD31 double-positive cells were most prominent in the large tumors, formed by admixed MCF-7 and HMLE-Snail cells (Figure 3D), suggesting that HMLE-Snail cells in the tumor milieu can stimulate MCF-7 cell growth and endothelial transdifferentiation, despite their own inherent lack of tumorigenic potential. The gene discussed is PECAM1; the disease is neoplasm.