FOXP1, also named as HSPC215, is a transcriptional repressor that plays an important role in the specification and differentiation of lung epithelium. It is essential transcriptional regulator of B cell developmen. A chromosomal aberration involving FOXP1 is found in acute lymphoblastic leukemia. FOXP1 is implicated in the pathogenesis of DLBCL and MALT lymphomas, through the identification of recurrent chromosome translocations that upregulate its expression levels and the correlation between high-level FOXP1 expression and poor prognosis. On initial examination, these data seem contrary to findings from the study of FOXP1 in epithelial malignancies, which suggest that it may represent a tumor suppressor gene. Convincing evidence linking the loss of the FOXP1 N-terminus and malignancy has already been generated through the study of recurrent viral integration sites that generate avian nephroblastomas.(PMID:18077790) The antibody recognize 2 smaller 60-65kd isoforms in mouse Lung.