A “flare” in thymidine salvage pathway activity measured in pemetrexed-sensitive NSCLC lines H460 (43.4±5.11%, p=0.0005) and H1299 (39.5±6.51%, p<0.0001) but not in TS overexpressed pemetrexed-resistant NSCLC cell lines H460R (-2.44±0.95%, p=0.421) and H1299R (-0.60±4.40%, p=0.870) in vitro using 3H-thymidine assays (Figure 2). Here, TYMS is linked to non-small cell lung carcinoma.