The majority of these genes (19 out of 30) have previously been associated with particular breast cancer subtypes (Rouzier et al, 2005; Hu et al, 2006; Parker et al, 2009) except 11 genes, including AFF3, DUSP4, ENO1, ERBB4, MMP7, MYB, PERP, RARA, SPP1, TFF1 and TFF3. Here, SPP1 is linked to breast cancer.