RT-PCR of FR isoforms in hematopoietic cells. RNA was isolated from LDMNC and CD34⁺ cells. RNA was reverse transcribed into cDNA and sequences unique to the , β, and γ FR isoforms were amplified. PCR reactions were separated on a 2% agarose gel, transferred to a nylon filter, and hybridized using the appropriate FR isoform cDNA. cDNAs for each FR isoform were used as positive controls and mouse RNA was used as a negative control. LDMNC and CD34⁺ cells express the FR-β and FR-γ isoforms but not FR-.