Fig. 2.

mRNA expression level of the reduced folate carrier (RFC) and dehydrofolate reductase (DHFR) genes. The expression of (A) RFC and (B) DHFR in six cell lines. The cells were incubated at IC₅₀ concentrations of methotrexate (MTX) for 72 hr and MTX untreated cells were used as controls. RFC and DHFR cDNA were prepared by reverse transcription from total RNA using a specific primer. Each bar represents the relative expression of the gene concerned versus the housekeeping gene, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), as determined by real-time RT-PCR.