Complete remission of acute promyelocytic leukemia can be achieved by treating patients with retinoic acid, and PML-RAR-a (promyelocytic leukemia-retinoic acid receptor alpha fusion protein) plays a major role in mediating retinoic acid effects in leukemia cells. The retinoic acid-induced gene, PRAM-1 (PML-RAR-a target gene encoding an adaptor molecule 1) encodes an adaptor protein which is expressed and modulated during normal human myelopoiesis. PRAM-1 expression is hindered by expression of PML-RAR-a. The 718 amino acid PRAM-1 protein contains eight N-terminal proline-rich repeats and several proline residues that are clustered as type I or type II SH3 recognition motifs. PRAM-1 demonstrates expression in hematopoietic tissues and lung.