Representative cases correlating methylation and re-expression before and after hydralazine treatment. A is a patient treated with 75 mg/day that demethylated and re-expressed the DAPK gene. B corresponds to a patient receiving 150 mg/day who showed only the methylated band pre-treatment, but both bands after treatment, which correlated with re-expression of MGMT. C is a 50 mg/day patient which failed to demethylate the DAPK gene and therefore lacked expression. D represents the distribution of informative cases. From the 128 genes/cases, 116 were RT-PCR positive regardless of the methylation status, hence were not informative. In the remaining 12 cases, nine demethylated and re-expressed the gene. (Reproduced from ref. 74. BMC Cancer 2005, 5:44).