PDPN and acute promyelocytic leukemia: Based on the demonstration that circulating levels of podoplanin is capable of identifying discrete subgroups of patients with other conditions [14, 15, 16, 17, 18], and that soluble levels of membrane proteins can serve as useful disease biomarkers [10, 11, 12, 13], we hypothesized that sPDPN levels might contribute to the differential diagnosis of APL from other forms of AML.