VTCN1 and neoplasm: In CD4 T cells, B7-H4 acts as a suppressor ligand, and effector T cells promote the conversion of conventional CD4 T cells to Tregs by modulating the Akt/FoxO pathway and increasing the Treg transcription factor Foxp3, thereby driving these cells to adopt both an activating and suppressive phenotype, as observed in several tumor models [114].