ERBB2 and breast cancer: For the breast cancer lines MCF-7 (hormone receptor positive), MDA-MB-453 (HER2 positive), SUM-190 (inflammatory breast cancer, HER2-positive) and MDA-MB-231 (partial mesenchymal, triple-negative breast cancer), as the number of spiked cells into HDB increased, the number of gene transcripts detected also increased (S1 Fig in S1 File).