Receptor expression analysis by immunohistochemistry showed that two of six tissues from BC patients (TT-44 and TT-217) were reported as ER- (ER-/PgR-/HER2+), while the remaining four were classified as ER+ (ER+/PgR +/HER2-) (Supplementary Fig. 13). The gene discussed is PGR; the disease is breast cancer.