Figure 2.

FOXP1 role in CD4+ T-cell differentiation. FOXP1 prevents naïve CD4+ T-cell differentiation into Tfh subset by inhibiting MAPK/ICOS axis and IL-21 expression. FOXP1 promotes CTLA4 and CCR7 expression, which inhibit Tfh formation and the migration to B-cell follicles, respectively. By repressing IL-9 and IL-21 expression FOXP1 prevents CD4+ T-cell differentiation into Th9 subset. FOXP1 is essential for iTregs differentiation and lineage stability likely through FOXP3 recruitment to its target genes. Yet, FOXP1 is dispensable for thymus Tregs differentiation and lineage stability.