Activation of Stat proteins by G-CSF through the chimeric receptors.

Parental UT-7/EPO cells and each chimeric clone were starved for 24 hours. Then the cells were stimulated with medium alone (−), 250 ng/mL G-CSF (G), or 10 U/mL EPO (E) for 15 minutes, and nuclear proteins were extracted for EMSA. SIE (A) and β-CAP (B) probes were used for detection of Stat1 and Stat3 DNA-binding activities, and Stat5 DNA-binding activity, respectively. Arrows A, B, and C indicate a homodimer of Stat3, a heterodimer of Stat1α and Stat3, and a homodimer of Stat1α, respectively.13 Arrow D indicates the Stat5 homodimer.13