FIG. 4.

An Epo pulse triggers EpoR signaling in CD36⁺/Epo⁻ EPCs. CD36⁺/Epo⁻ EPCs were pulsed with Epo (3 U/ml) for different lengths of time prior to B19V infection. Analysis was performed immediately after treatment and prior to B19V infection. CD36⁺/Epo⁺ EPCs expanded in Wong medium were used as controls. (A) For each treatment group, phosphorylation of EpoR and Jak2 prior to B19V infection was assessed by flow cytometry immediately before infection. Primary antibodies used were anti-pEpoR (Tyr 456) (Santa Cruz Biotechnology, Inc., Santa Cruz, CA), anti-pJak2 (Tyr 1007) (GenScript, Piscataway, NJ), and anti-B19V NS1 (12). (B) Quantification of data shown in panel A, with average mean fluorescence intensities (MFI) indicated by the bars and the background fluorescence indicated by the reference line. bkg, secondary antibody only.