FIGURE 1.

Gene expression in human primary erythroid progenitor cells. A, cell proliferation (top) and % benzidine positive cells (bottom) following 12 days of treatment with EPO in primary erythroid progenitor cell cultures from Patient A with excessive erythrocytosis (solid line) compared with normal control (dashed line) treated with 0.01 to 10 units/ml of EPO as indicated. Data represent mean ± S.D. B, expression of EPO-R and β-globin are shown for corresponding cultures treated with 1 unit/ml of EPO and corresponding cultures from Patient B (solid line) and Patient C (dashed line) with the JAK2V617F mutation associated with polycythemia vera (right) and treated with 1 unit/ml of EPO. C, colony assay of BFU-E and CFU-E in peripheral blood of patient and control in culture. Data represent mean ± S.D. (n = 3), and * indicates p ≤ 0.05.