(S (S (BASENP (DT A) (NN gene)) (VP (VBZ has) (VP (VBN been) (VP (VBN discovered) (SBAR (WHNP (WDT that)) (S (VP (VP (VBZ turns) (BASENP (NN stem) (NNS cells))) (PP (IN into) (NP (NP (BASENP (NN cancer) (NNS killers)) (COMMA ,) (BASENP (JJ promising) (JJ new) (NNS treatments))) (SBAR (WHNP (WDT that)) (S (VP (VBP boost) (NP (NP (BASENP (DT the) (NN body) (POS 's)) (NN ability)) (SBAR (S (VP (TO to) (VP (VB destroy) (BASENP (NNS tumors))))))))))))))))))) (PERIOD .))