SPP1 and breast cancer: A detailed knowledge of this complexity gives a fair idea about friends (such as PPARγ, c/EBPα, GATA3, KLF2, FoxA2, SFRP1 etc.)and foes (such as c/EBPδ, KLF5, GATA2, FoxC2 and SPP1) in the process of BC and of where and how we could use this information in targeting BC.