Figure 9. Characterization of compound 17 and PMX growth inhibition in R1–11 sublines differing in hPCFT and hRFC expression. Cell proliferation inhibition was measured for R1–11-PCFT4 (expresses hPCFT but not hRFC) and -RFC6 (expresses hRFC but not hPCFT) cells treated with PMX (A) or compound 17 (B) over a range of concentrations in complete folate-free RPMI1640 in the presence of 5-CHO-THF at 25 nM for 96 h. Cell densities were measured with CellTiter Blue^TM fluorescence dye and a fluorescence plate reader. Results were normalized to cell densities in the absence of drug. From Kugel Desmoulin et al.¹²