As proliferating neoplasms are typified by increased genomic instability38, we isolated uPAR−/int-β1− and uPAR+/int-β1+ CTC subsets from BCBM vs. no BCBM patient pairs (both ER+/PR+/HER2−) and extracted genomic DNA from these cells. The gene discussed is ERBB2; the disease is neoplasm.