FOXP1 and marginal zone lymphoma: Importantly, FOXP1 is a marker of adverse outcome in other B-cell malignancies, including marginal zone lymphoma (25), chronic lymphocytic leukemia (26), and follicular lymphoma (27, 28), Foxp1 expression patterns (both full length protein and smaller isoforms) and its repression of MHC-II, previously observed in human ABC-DLBCL (9), are both conserved in the murine A20 model.