Schematic representation and FACS analysis of chimeric receptors expression.

(A) Schematic representation of P-R and chimeric receptors PM-R and PE-R. P-R is the normal rabbit prolactin receptor; PM-R contains the extracellular part of the rabbit prolactin receptor fused to the transmembrane and the intracellular domain of murine MPL; PE-R is composed of the extracellular part of the rabbit prolactin receptor fused to the transmembrane and the intracellular domain of murine EPO-R.22 All constructs were subcloned into the MSCV retroviral vector. (B) FACS analysis of the expression of the chimeric receptors in fetal liver cells. Cells were stained with the anti–PRL-R monoclonal antibody M110 (gray peak) or isotype control antibody (open peak) 48 hours after infection. Second-step antibody was a PE-conjugated goat anti–mouse F(ab′)2. The percentage of fetal liver cells expressing P-R, PE-R, and PM-R is indicated.