High expression of TS, DHFR and GARFT in squamous cell lung cancer and some of lung adenocarcinoma was proven to reduce chemosensitivity of cancer cells to pemetrexed, and pemetrexed was inefficient in patients with this histologic subtype of NSCLC (Scagliotti et al. 2009; Chattopadhyay et al. 2007; Hanauske et al. 2007; Wang et al. 2014; Ceppi et al. 2006). The gene discussed is TYMS; the disease is non-small cell lung carcinoma.