All seven TNBC cell lines tested expressed high annexin A1 levels (at least twice the level in the MCF7 reference cell line), whereas only one of five ER+ (20%), and two of six Her2/neu+ (33%) breast cancer cell lines had higher expression of annexin A1 relative to reference MCF7 cell line ((Fig 2A–2D, S1 Fig). This evidence concerns the gene ESR1 and breast cancer.