FOXP3 and neoplasm: Secondly, as a tumor suppressor, FOXP3 represses many key target genes in cancer development and progression, such as HER2/ERBB2 [12], BRCA1 [13], SKP2 [14], and CD44 [15], providing a strong link between FOXP3 and cell cycle regulation as well as FOXP3 and DNA repair system.