In contrast to its inhibitory effects on survivin promoter activity, FL118, even at a 10 nM level, showed no inhibitory effects on luciferase activity driven by control promoters of the cyclin-dependent kinase inhibitor p21WAF1/CIP1 (p21), dihydrofolate reductase (DHFR), human thrombin receptor (HTR), or thymidine kinase (TK) genes in various cancer cell types with different p53 status (Fig. 4c–e). This evidence concerns the gene DHFR and cancer.