FOXP1 and neoplasm: One such marker is FOXP1 (forkhead box P1), a transcription factor belonging to the forkhead box family,3 that is involved in B-cell development.4 The FOXP1 gene maps to a tumor-suppressor locus at 3p14.1, and although a tumor-suppressive role for FOXP1 has been identified in certain malignancies,5 other studies have suggested an oncogenic role in lymphoma.