Changes in responsiveness to EPO or TPO in the UT-7/GM cells maintained with TPO or EPO. UT-7/GM cells were cultured with TPO (100 ng/mL), or EPO (10 U/mL). One month later, the cells were obtained and plated at a density of 10⁴/well in IMDM supplemented with 5% FCS, and cultured with increasing concentrations of GM-CSF (A; 0.01 to 10 ng/mL), EPO (B; 0.01 to 10 U/mL) or TPO (C; 0.1 to 100 ng/mL). MTT reduction was measured after 3 days of culture. The values represent the mean ± SD from triplicate cultures. UT-7/GM cells, ○; UT-7/GM cells cultured with EPO for 1 month, □; UT-7/GM cells cultured with TPO for 1 month, ▵.