OB-R expression in different FAB subtypes of newly diagnosed AML. Long (▩) and short (□) OB-Risoforms were identified using specific primers as described in Materials and Methods. Amplification and detection was performed using³²P-dCTP incorporation. Results are shown as percentages of positive cases in each category. The long isoform only was detected in one case classified as FAB M0, and both isoforms were present in one case classified as FAB M5 (not shown).