The tissue kallikrein gene family consists of 15 genes tandemly arranged on 
human chromosome 19q13.4. Most kallikrein genes are characterized by aberrant 
expression patterns in various human cancers, a feature that makes them ideal 
cancer biomarkers. In the present study, we investigated the effect of the 
epigenetic drug compound 5-aza-2'-deoxycytidine on the expression of 
downregulated kallikrein genes in prostate, breast, and ovarian cancer cell 
lines. Reactivation of multiple kallikrein genes was observed, although some of 
these genes do not contain CpG islands in their genomic sequence. Epigenetic 
regulation provides a new mechanism for the pharmacological modulation of 
kallikreins in human cancers with putative therapeutic implications.