( BrdU ( ( was ( ( incorporated ( into ( nuclear DNA ) ) ) ( during ( ( the ( S phase ) ) ( of ( ( DNA synthesis ) ( in ( the ( cell cycle ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP BrdU)) (VP (VBD was) (VP (VBN incorporated) (PP (IN into) (NP (JJ nuclear) (NN DNA))) (PP (IN during) (NP (NP (DT the) (NNP S) (NN phase)) (PP (IN of) (NP (NP (NNP DNA) (NNP synthesis)) (PP (IN in) (NP (DT the) (NN cell) (NN cycle))))))))) (. .)))
BrdU was incorporated into nuclear DNA during the S phase of DNA synthesis in the cell cycle.
(ROOT (S (PP (IN During) (NP (NP (DT the) (NN synthesis) (NN phase)) (PP (IN in) (NP (DT the) (NN cell) (NN cycle))))) (, ,) (NP (NN dna) (NN replication)) (VP (VBZ occurs)) (. .)))