SLC29A1 and non-small cell lung carcinoma: Specifically, in vitro studies have shown a significant correlation between basal expression levels of hENT1 and gemcitabine IC50 values in twenty-two NSCLC cell lines, and the use of the nucleoside transport inhibitors nitrobenzylmercaptopurine riboside and dipyridamole resulted in significantly reduced sensitivity to gemcitabine (Achiwa et al., 2004).