vMCF-7∆Raf1 1GX xenografts exhibiting CIN showed tumor cell heterogeneity for NOTCH3 expression, indicating that NOTCH3high-expressing subclones may arise from the primary tumor and promote distant metastasis owing to their higher stemness capacity, in agreement with the recent finding that metastatic clones disseminate early from primary breast tumors [49]. The gene discussed is NOTCH3; the disease is neoplasm.