( They ( ( ( do not ) ( ( do not ) ( undergo ( cell division ) ) ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBP do) (RB not) (VP (VBP do) (RB not) (VP (VB undergo) (NP (NN cell) (NN division))))) (. .)))
They do not do not undergo cell division.
(ROOT (S (S (NP (DT All) (NNS cells)) (VP (VBP undergo) (NP (NN cell) (NN division)) (PP (IN during) (NP (DT a) (NN lifetime))))) (, ,) (CC but) (S (SBAR (WHADVP (WRB when)) (S (NP (DT this) (NN process)) (VP (VBZ is) (ADVP (RB out)) (PP (IN of) (NP (NN control)))))) (, ,) (NP (NN cancer)) (VP (VBZ results))) (. .)))