FOXP1 represses its target genes by forming homodimers or heterodimers with FOXP2 and FOXP4 [39], it has been suggested to be both a tumor suppressor candidate and potential oncogene, because of its differential expression levels in distinctive types of tumors, including B cell lymphomas [40], breast cancer [41, 42], endometrial cancer [43], prostate cancer [44], non-small cell lung cancer [38] and renal cell carcinoma [45], the loss of FOXP1 in breast cancer has been associated with shorter survival times [42]. Here, FOXP4 is linked to breast cancer.