WEHI-3B myelomonocytic leukaemia cells secrete a haemopoietic cell growth factor (HCGF) which facilitates the proliferation and development of multipotential stem cells and committed progenitor cells. Several cloned, nonleukaemic cell lines (FDC-P cells) are absolutely dependent on HCGF and die in the absence of it. In these cell lines, factor dependence is associated with the ability of HCGF to increase glucose uptake, thereby controlling glycolytic flux and intracellular ATP levels. We have now investigated the effects of HCGF on glucose uptake in WEHI-3B cells. At 20 degrees C 2-deoxyglucose uptake could be stimulated by the addition of HCGF to the extracellular medium. L-glucose uptake was markedly lower than 2-deoxyglucose uptake and did not respond to the addition of HCGF. At 37 degrees C no HCGF stimulation of 2-deoxyglucose uptake was found. However, at this temperature HCGF release from WEHI-3B cells was markedly higher than at 20 degrees C. Our experiments indicate that HCGF stimulates the glucose transport system in both WEHI-3 cells and FDC-P cells. The similarities between the WEHI-3B cell and FDC-P2 cell polypeptide phenotype were investigated using two-dimensional isoelectric focussing/poly-acrylamide gel electrophoresis. This revealed a high degree of correlation between the two cell types in their protein constituents, indicating a close relationship between the normal and leukaemic cells. These similarities between WEHI-3B cells and FDC-P2 cells are considered and their relevance to haemopoiesis and leukaemogenesis is discussed.