(S (S (BASENP (NN Testing)) (VP (VBD showed) (SBAR (IN that) (S (BASENP (NN DCA)) (VP (VP (VBD attacked) (BASENP (NN cancer) (NNS cells))) (CC but) (VP (VP (VBD did) (RB not)) (VP (VB attack) (BASENP (JJ healthy) (NNS cells))))))))) (PERIOD .))