Established at diagnosis of a 68-year-old male with acute myeloid leukemia (AML M6) secondary to myelodysplastic syndrome (MDS, subtype refractory anemia with excess of blasts, RAEB) in 1989; Cells were described to be proliferatively responsive to GM-CSF and IL-3. Cells have been shown to synthesize haemoglobin when GM-CSF or IL-3 is substituted by erythropoietin (Epo). They have been reported to be positive for leukocyte common antigen (CD45) and some multilineage markers such as CD13, CD33 and CD34, but are negative for T- and B-cell antigens and mature myelomonocytic antigens. Due to their reaction with some monoclonal antibodies recognising erythroid and platelet glycoproteins it has been suggested that F-36P has a multilineage phenotype.