Measurement of intracellular free calcium concentration upon exposure to Epo and ionomycin in the bone marrow cell fractions. Bone marrow cells from G1-HRD-GFP transgenic mice were analyzed for their intracellular free calcium concentration after supplementation of Epo (10 U/mL) or ionomycin (3 μg/mL) by Indo-1 flow cytometry. The percentages of cells containing IFC in each fraction are indicated.