A team of researchers and clinicians has published the first proof that a targeted nanoparticle -- used as an experimental therapeutic and injected directly into a patient's bloodstream -- can traffic into tumors, deliver double-stranded small interfering RNAs, and turn off an important cancer gene using a mechanism known as RNA interference. Moreover, the team provided the first demonstration that this new type of therapy can make its way to human tumors in a dose-dependent fashion.