Expression of FGFR1 and FOP genes. RT-PCR products were obtained from a variety of tissues and normal and tumoral hematopoietic cells using specific primer pairs of each gene. Each panel is a photograph of the ethidium bromide-stained agarose gel in which PCR products were electrophoresed. Labels at the top of rows indicate the source of the material. The first row corresponds to cDNA controls: a 2.5-kb FGFR1 cDNA (pFLG-16) containing the complete coding sequence (upper panel)49 and the FOP cDNA clone zs55g02 (middle panel), respectively. The other rows correspond to RNAs from a variety of lympho-hematopoietic cell lines (listed in Materials and Methods) and mature peripheral (T lymphocytes, B lymphocytes, and monocytes) blood cells purified as indicated in Materials and Methods. β2 microglobulin (β2M) amplification was used as a control.