EPO receptor expression on CD13⁺ blasts and in vitro proliferation of CD13⁺ cells in response to EPO.

Upper panels (A) demonstrate gating on blasts defined by forward scatter characteristics (FSC) versus side scatter characteristics (SSC) (left) and coexpression of the EPO receptor with CD45 (center) and CD13 (right) on cells in the gated region. Lower panels (B) demonstrate the incorporation of BrdU into CD13⁺ cells in the absence (left) and presence (right) of EPO. Increased DNA synthesis is seen in CD13⁺ cells in the presence of EPO.