MKI67 and breast neoplasm: However, high FBXO28 levels were also found to be associated with poor prognosis in particular patient subgroups, including low proliferative luminal A tumours and in highly proliferative (high Ki-67 levels), poorly differentiated breast tumours (Fig 8E and Supporting Information Fig S7E), presumably tumours with hyperactivation of MYC (Xu et al, 2010).