We also examined the possible effect of pemetrexed on the expression levels of apoptosis-related molecules in both Mock and TS-overexpressing cells, but we found that pemetrexed did not substantially alter the abundance of such proteins including that of XIAP (data not shown), which we previously identified as having a key role in TS depletion-induced apoptosis in NSCLC cells (Takezawa et al, 2010). The gene discussed is XIAP; the disease is non-small cell lung carcinoma.