Researchers continue to search for how they can inhibit cancer metastasis as it can severely worsen prognosis, even if the primary tumor responded well to therapy. Researchers at Università degli Studi di Torino and collaborators previously showed that injecting an RNA aptamer targeting the miRNA miR-214, called anti-miR-214 sponge, reduced metastasis of tumors to lungs and liver. One drawback of this potential therapeutic approach was that the inhibitor oligo could enter all cells, not only tumors.