In this study we have investigated the relevance of these proposed mechanisms for hTS regulation and assayed their kinetics during 5-FU treatment in the ovarian cancer cell line 2008 and the corresponding cisplatin resistant- and 5-FU cross-resistant subline C13* that shows higher steady-state expression level of the enzymes of the folate cycle [20]. This evidence concerns the gene APCDD1 and ovarian carcinoma.