Colorectal, breast and the HOP92 lung cancer cell lines commonly demonstrated high expression levels of hENT1, low-medium levels of dCK and variable expression of both cN-II and DNA polymerase, and HOP62 lung and ovarian cancer cell lines showed low expression of the transporter hENT1 and medium cN-II and DNA polymerase expression; however, no obvious correlation between drug sensitivity and mRNA expression levels of these metabolic factors was identified. This evidence concerns the gene NT5C2 and lung carcinoma.