The word interferons is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 16
Highest Scoring Words With Friends™ Plays In The Letters interferons
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Seven Letter Word Alert: (49 words)
entries, erotise, estrone, ferrets, ferries, ferrite, foister, forints, forseen, forties, froster, inerter, inferno, intense, interns, intoner, intones, introns, ironers, nitrene, nonfire, nonfree, norites, oftener, orients, refiner, refines, refires, refrets, refries, reinter, rennets, renters, rerents, rerinse, restore, retires, retries, rioters, roister, snifter, snorter, sterner, stonier, tenners, tension, tinners, trienes, triones