RT-PCR analysis of expression of α chain of GM-CSFR in ECs (lanes 3 to 5) and U937 cell line (lanes 7 to 9). One microgram of total RNA was reverse-transcripted and amplified with GM-CSFRα1 –(lanes 4 and 8), GM-CSFRα2– (lanes 5 and 9), and β-actin– (lanes 3 and 7) specific oligonucleotides. Amplified products were run in an ethidium bromide-agarose gel and visualized by UV. In lane 1, molecular weight have been runned. Lanes 2 and 6 represent two control experiments performed with RT-PCR mixture without cell RNA. This experiment is representative of five performed with similar results.