PDGFB and breast cancer: Consistent with this finding, we observed several AR pathway regulators are expressed at significantly lower levels in TCGA basal subtype patients compared with other subtype breast cancer patients, including AR, CREB3L1, CREB3L4, EGF, PDGFB, PDGFRB, PIK3R1, PTEN, RB1, ZEB1 (Additional file 13: Figure S6).