Cell cycle regulators Wee1, CDC25A/B and Emi-1 are other known βTrCP substrates [12] which play an oncogenic role, specifically the overexpression and up-regulation of CDC25A/B and Emi-1 has been accounted for in human tumour cell lines and cancers such as ovarian, colorectal and breast cancers [25,26]. Here, FBXO5 is linked to breast cancer.