ERBB2 and breast cancer: These plots indicate that the newly derived factors capture the most important known breast cancer biology: 1) the clinically relevant ER+/ER- split as represented by Factor 1 (correlating with the TCGA ER factor); 2) the normal-like subtype as identified by Factor 2 (correlating with the TCGA Normal-like factor); 3) the Luminal B subtype as represented by Factor 7 (correlating with the TCGA Luminal-Proliferative factor) and finally 4) the HER2 subtype as captured by Factor 8 (correlating with the TCGA HER2 factor).