In addition to its chromatin binding properties, the PWWP domain also serves as a site for protein–protein interactions, as evidenced by our previous report that in prostate cancer (PCa) cells this domain facilitates the direct interaction between DFS70/LEDGF and the methyl CpG binding protein MeCP2, which may function as a transcriptional repressor or activator depending on the context [30]. The gene discussed is PSIP1; the disease is Familial prostate cancer.